Saturday, June 30, 2007
Limited Edition
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The Ruby Mines In Mogok In Burma
2007: Today Mogok still look pretty much the same. In Burma, everything is slow. The way of life + the ruby intrigue + the traditions still attracts a lot of Westerners to this one-of-a-kind gem deposit in the world. Edward Gubelin describes the way of life of the Burmese in a colorful tone + he happened to be one of the lucky Westerner to visit Mogok in the 1960s and collect samples from the source for his research.
(via The Journal of Gemmology, Vol.IX,No.12, October 1965) E Gubelin writes:
The ruby mines in Burma have been known for centuries and the large mining district of Mogok above a lovely lake has always proved to be of great interest because of the wonderful rubies found there. Mogok itself is full of mysteries and whoever goes there for the first time is delighted with its beautiful streets and the soft music of the bells from the temples and pagodas. The author visited this valley for the first time three years ago, after his second stay in Ceylon, and was in no way disappointed.
The western mountainous Shan-plateau rises towards the east over the middle Irrawaddy valley; there are mountains in the north and the lake to the south. The valley of rubies is narrow and long and towards its lower end lies Mogok. It is about 700 km north of Rangoon and 150 km north-east of Mandalay, the last residential town of the Burmese kings. Only 145 km east of this town is the frontier of Burma with China. The township lies about 1500 meters above sea level and is surrounded by mountainous sometimes reaching a height of 2500 meters, all covered with thick jungle. The climate is agreeable, although there is a great difference of temperature between the very hot hours around noon and the cold nights. It rains often and rainfall during the summer months of the monsoon can reach more than 250 mm. It is very rare that the temperature during the winter drops to freezing point.
At the time of writing the visa given to foreigners does not exceed 24 hours, which makes it impossible to leave Rangoon, but before this additional difficulty arose, there were several ways of going to Mogok. Mandalay can be reached by a slow train taking two days for the trip or by a four to six hour flight by the Union of Burma Airways. From Mandalay there are again several ways of reaching Mogok. One can fly on to Momeik and if one has any friends in Mogok ask them to fetch one by jeep. One then travels along a good mountainous road. But as it was well known that many robberies occurred at the time of the visit, the author thought it safer to use the official coach. The coach uses many dusty roads, full of ox-carts, along the Irrawady valley on a very bumpy road and then slowly rises on a narrow but good road through beautiful mountain country towards Mogok, where it arrives twelve hours later. Four days after the author’s safe arrival three private jeeps traveling down the valley were ambushed and robbed.
There are neither hotels nor boarding houses in Mogok, and if one wants to stay in a bungalow for government officials, one has to supply one’s own bed linen and either cook one’s meals, or eat in one of the small Chinese stalls. The author was very lucky and was invited to stay in the house of his Burmese interpreter and agent and was thus able to take part in the daily life of the family. They were all very kind and hospitable and tried to make the visit as agreeable as possible. There are only a few streets in Mogok, the most important being macadamed and at their sides are beautiful houses. Most of these are made of wood, some using teak. In the last few years a few villas were erected from stone. Around the town and in the surrounding villages the houses are made of interwoven bamboo sticks, build on piles. These airy rooms usually form the workshop and the gems are polished here. Unfortunately only the older houses are covered with straw, tiles or brick, the newer houses being covered with corrugated metal sheets, which are not attractive. Many small shops and stalls along the two main roads form the business quarter, where one can buy most consumer goods from a tea cup to a loupe or a washing basket made of bamboo strips to household articles made of plastic. Of the greatest interest is the bazaar, where there is a market every five days and the inhabitants of the surrounding districts and mountains gather in their colorful costumes to sell vegetables, herbs, baked articles, tobacco and all sorts of homemade goods and who seldom return home without looking at, or even buying a few rubies. One must also mention the waterworks and sewage arrangements, which work very well, and a very old-fashioned electricity plant which sells its electricity (220V) during the day to the mines and only after 6 pm to the townspeople, so that one can only then use the electric light. It is then used so much that the voltage falls from 220V to 110, so that one can hardly read. The foreign visitor is well advised to take a torch along together with a sufficient supply of batteries. There is no official waste disposal, so it is not surprising that there are often cases of malaria, dysentery and typhoid. The visitor must be careful in every respect. Apart from various nature-cures and quacks, there are also a few good doctors in Mogok, but hospitals, old people’s homes and orphanages are not necessary since all these services are given by the family. There is always much life in the streets. Most goods are still transported on a shoulder-yoke or by ox-cart. There are many bicycles, and a few cars and vans. The riche mine owners have land-rovers, and there are various jeeps which are used as taxis to which transport people to the surrounding villages.
Although the whole district is only a few square miles and Mogok itself only a small town, there must be about 20000 people living in the district. The inhabitants are very mixed: apart from Burmese, there are Ghurkas, Hindus, Chinese and the romantic looking people from the Schan tribe. On each side of the street, in market places, in front of the tea houses and bazaars, there are small groups of squatting women showing each other small brass bowls with rubies. One soon has the impression that the whole population from the earliest youth to the oldest age is involved in the prospecting, production and sale of rubies, whether as a mine worker, mine owner, gem merchant, polisher, host or tradesman. The people are very friendly, helpful and open: the few that speak a foreign language like to talk to visitors.
The famous ruby mines are secondary deposits, that is, they have been brought down into the valley from decomposed primary deposits. Such alluvial deposits are found in most of the smaller and larger valleys of the district, and everywhere there is prospecting for rubies. Mogok lies in the lower part of a larger valley on what used to be the most profitable deposits. When the population realized this, they moved their township to the lower part of the hills so that they could mine the rubies in the valley. When there were no rubies, the craters which were formed by the mining operations filled with water, forming the lovely Mogok Lake, which today beautifies the valley. In the neighboring valleys the yellow clay is full of holes, and looks like a volcanic field of craters.
Prospecting and mining licenses are only given to Burmese. The owner who wants to open a small mine registers his intention with the district officer, who examines the claim. Depending on the size of the mine, the owner pays several hundred Kyats (1 Kyat = 1s. 6d) for the license. The license for a so-called machine-mine is about 1000 Kyats. The license cannot buy the land, which is only rented from the state for mining purposes. When mining operations are finished it is not necessary to fill in the craters and holes, contrary to practice in Ceylon. This is a defect in the law and leaves the valleys full of holes and unsuitable for agricultural purposes. For each employee the mine owner pays a monthly license fee of 10 Kyats and as a receipt obtains a small oval disc, which each miner must wear to facilitate inspection. Most mining is still done by hand with the help of water—without the local water supplies the mining could not have developed as it has.
Most of the stones are found in open-cast mines. The small narrow holes are widened with sticks and spades. The earth is put into woven bamboo baskets and lifted to the surface where it is emptied onto a heap. When the ruby-containing-the byons layer is reached, a byon heap is started, whence the earth is transported to the washing hole. Within a few weeks the small hole has become a mine of about 100 meters in diameter, perhaps reaching a depth of 20-30 meters, when the water level is reached. From a neighboring water tank water is hosed over the byon layers. The softened earth is pumped, either electrically or with a petrol engine, to a washing plant built from wood or stone and measuring perhaps four square meters and consisting of a basin which is about ½ -1 meter deep and from which there is a step-like arrangement of locks. Usually the earth is mined during the afternoon and then worked and washed the following morning, so that the gem-containing byon earth can settle during the night. In the morning clear water is pumped into the basin, washing away the top layer of waste earth, whilst the heavier gems settle in a series of boxes. During this time the washers stir up the deposit, so that it may be rinsed with water and carried away to a lower lock. Starting at the top the washers scoop some of the deposit up with their hands and shake it in a rough wire-mesh sieve to get rid of the large stones, the finer and medium deposit is then put into a shallow basket, from which the so-called therbat is put on the sorting table. The sorter, who in the case of small mines is the same man as the owner, combs through the therbat with a wooden comb and picks out the rubies. Just as the washing of the deposit below the last lock is free to everybody, so friends and relatives look through the waste from the sorting table either without remuneration or against a small fee. In this way all the innumerable small rubies which are used for adorning pieces of jewelry are won.
About 10 km west of Mogok, in the small township of Kathe and Kyatpyin, the valley is very dry and water not abundant and thus a new method of mining has developed. Parallel to each other long narrow trenches are dug, which are often connected under the surface by horizontal channels. These workings are usually co-owned by three to five men. At the opening of the shaft one or two winches are erected which help to bring to the surface the baskets which have been filled by a miner with the gem-containing earth or byon. The last man carries the basket either to the slack heap or the byon heap, which grows during the dry months from October to the end of April, and then is washed and worked during the summer monsoon season. Characteristic of the whole district is that there are no specially rich localities, but the precious stones can be found anywhere or everywhere, in a brook, in a rice field or in a mine. Ruby is the most looked for stone, but not the most common gem; there is one ruby found to every five spinels. There are fields which yield mainly rubies, other spinels, or moonstones or sapphires, and it has been known that certain mines produce certain colors, but in one basket of byon all types of unusual gems can be found. For the gem collector and gemologist the mines of Mogok are a real paradise, for apart from rubies, spinels, sapphires, moonstones and peridots, which are found in quantities, one also finds almandine garnets, amethysts, beryls, chrysoberyls, spessartites, topazes, tourmalines, zircons and citrines and mentioning some rare gems the following have been found as well: amblygonite, blue apatite, danburite, diopside, disthene, enstatite, violet fluorite, fibrolite, iolite, kornerupine, scapolite, titanite and others. The inhabitants of the districts know very little of these various gem types, and it is not surprising that one is often offered these stones under a wrong name. For instance, pink scapolite is known as pink moonstone and every yellow to brown stone as topaz. But if one knows anything about these stones, and in addition even possesses a refractometer, one can enrich a collection with many beautiful and rare specimens. There is a trade with rough rubies everywhere, along the mines, along the streets, in the bazaars, in the market places, in the backyards, and, of course, in the houses of the mine owners and gem dealers. Because there are always people looking on, a sign language using the fingers has been developed, with which one can express all numerals. Offers and acceptances are communicated under a cloth or in the wide sleeves of the engyis worn by the natives, so that none of the onlookers and strangers are any the wiser.
A large part of the gems found in Mogok and surrounding district are cut locally. Taking into account the very primitive grinding wheels the quality of the produced goods is fairly good, and quite usable according to Western standard. Depending on the resulting style the cutter chooses his tools and his method. Small stones, which are made into small cabochons, are usually worked by children and young girls. The rough stones are fixed onto a bamboo stick; five to ten of these sticks are held in each hand, then held onto a horizontally rotating grinding wheel. It is most instructive and enjoyable to watch how the hands lead the sticks on the wheel and how a few minutes later a number of cabochons are produced.
Large cabochons and star stones are produced by men who use special grinding boards with a carborundum covering; these boards have grooves of various widths in them which are also covered with various grades of carborundum. The rough stones are again fixed on bamboo sticks, which are pushed forwards and backwards in these grooves using finer and finer carborundum until the finished cabochons show a smooth highly polished surface.
The smaller facets are made by young boys, girls and women. The stones are fixed in a simple dop and the first facets are ground roughly on a carborundum board. After they have received their first rough shape they are fixed again onto sticks which can be held in a simple dop. The facets are then cut and polished on horizontally rotating grinding wheels, and from time to time checked by eye to ensure that they are even.
The large faceted stones are produced by a similar method, but only older and experienced cutters are allowed to make them. The advice of these cutters is welcomed by owners and dealers alike. The grinding wheels are rotated with the feet by a sort of treadle arrangement, as the old-fashioned electricity plant is not powerful enough to work all the wheels. Special large crystals are sometimes sawn before being cut and polished. In the whole of the district there is only one specialist who does this; he uses a machine which looks similar to an old sewing machine. It has a horizontal spindle on which a diamond sawing wheel is rotated by a foot pedal. Although the tools of their trade are primitive, most cutters are masters of their craft and know how to obtain the best results from an irregularly colored stone, or how to place inclusions or cracks in the stone into a position where it is extremely difficult to see them. Often stones with cracks are put into peanut oil so that cracks become invisible. It is also amazing how the Mogok cutters produce stones with even facets and regularity of geometrical planes. All these points show that their technical knowledge is greater than that of the Ceylonese cutters.
The buying of gems in Mogok is a time consuming but very interesting business, which needs absolute concentration and denial of western habits. It takes a long time for one to meet the people who sell the goods one wishes to buy. Once one has found them it needs a lot of patience until the stones are shown. Of the thousands of stones which are shown, only a few are of really good gem quality. Doubtless the families keep the very best stones to themselves and evens in Burma have shown the wisdom of this. But now and then a very fine gem is offered for sale. When the author was in Mogok, only after days of bargaining did the most important dealers show him a really good ruby or sapphire. The author was thus very impressed by the rarity and value of the finest gems. Most dealers show many lots of smaller and medium as well as a few larger rubies, but these lots are only shown one at a time, and much time and patience is needed to look through them all and wait for the appearance of better stones. The deal is never finalized without the wife giving her consent. The women of Mogok not only wear the jewels, they are also important in the mining, production and trade. In fact, the female gem merchants in Mogok are much tougher than the men and understand the fine qualities especially well.
The unit of weight is not the carat, but the Burmese rattie (1rt = 0.90 cts). The price of fine rubies has risen very sharply during the last 15 years. This has been caused not only by the increase in rarity, but also by the purchases of Indian merchants who pay too high a price for the rubies, as they earn some money on the transaction of the rupee-Kyat exchange. The inflationary and political uncertainities in Burma also play a part. The Burmese government is nationalizing all industries and has now also forbidden private businesses such as gem mining and dealing. The gem production is guarded by the army and all gems have to be sold to the Petrol and Mineral Development Corporation. The PMDC has now tried to sell the gems on the western markets, but was unsuccessful because of the low quality offered. During the first half of last December 180 gem dealers from 25 countries were invited to an officially organized sale, but most of these visitors were disappointed because of the poor quality offered to them. Many did not purchase anything as the poor qualities cannot be resold on the western markets. It seems a pity that most important gem producing countries have made free trading so difficult. For these countries the loss is usually only a few percent, while the loss in the free world is quite noticeable. These circumstances do not help to make the gems any cheaper, and every jeweler who has a few fine specimens is proud of them and knows how to treasure them.
(via The Journal of Gemmology, Vol.IX,No.12, October 1965) E Gubelin writes:
The ruby mines in Burma have been known for centuries and the large mining district of Mogok above a lovely lake has always proved to be of great interest because of the wonderful rubies found there. Mogok itself is full of mysteries and whoever goes there for the first time is delighted with its beautiful streets and the soft music of the bells from the temples and pagodas. The author visited this valley for the first time three years ago, after his second stay in Ceylon, and was in no way disappointed.
The western mountainous Shan-plateau rises towards the east over the middle Irrawaddy valley; there are mountains in the north and the lake to the south. The valley of rubies is narrow and long and towards its lower end lies Mogok. It is about 700 km north of Rangoon and 150 km north-east of Mandalay, the last residential town of the Burmese kings. Only 145 km east of this town is the frontier of Burma with China. The township lies about 1500 meters above sea level and is surrounded by mountainous sometimes reaching a height of 2500 meters, all covered with thick jungle. The climate is agreeable, although there is a great difference of temperature between the very hot hours around noon and the cold nights. It rains often and rainfall during the summer months of the monsoon can reach more than 250 mm. It is very rare that the temperature during the winter drops to freezing point.
At the time of writing the visa given to foreigners does not exceed 24 hours, which makes it impossible to leave Rangoon, but before this additional difficulty arose, there were several ways of going to Mogok. Mandalay can be reached by a slow train taking two days for the trip or by a four to six hour flight by the Union of Burma Airways. From Mandalay there are again several ways of reaching Mogok. One can fly on to Momeik and if one has any friends in Mogok ask them to fetch one by jeep. One then travels along a good mountainous road. But as it was well known that many robberies occurred at the time of the visit, the author thought it safer to use the official coach. The coach uses many dusty roads, full of ox-carts, along the Irrawady valley on a very bumpy road and then slowly rises on a narrow but good road through beautiful mountain country towards Mogok, where it arrives twelve hours later. Four days after the author’s safe arrival three private jeeps traveling down the valley were ambushed and robbed.
There are neither hotels nor boarding houses in Mogok, and if one wants to stay in a bungalow for government officials, one has to supply one’s own bed linen and either cook one’s meals, or eat in one of the small Chinese stalls. The author was very lucky and was invited to stay in the house of his Burmese interpreter and agent and was thus able to take part in the daily life of the family. They were all very kind and hospitable and tried to make the visit as agreeable as possible. There are only a few streets in Mogok, the most important being macadamed and at their sides are beautiful houses. Most of these are made of wood, some using teak. In the last few years a few villas were erected from stone. Around the town and in the surrounding villages the houses are made of interwoven bamboo sticks, build on piles. These airy rooms usually form the workshop and the gems are polished here. Unfortunately only the older houses are covered with straw, tiles or brick, the newer houses being covered with corrugated metal sheets, which are not attractive. Many small shops and stalls along the two main roads form the business quarter, where one can buy most consumer goods from a tea cup to a loupe or a washing basket made of bamboo strips to household articles made of plastic. Of the greatest interest is the bazaar, where there is a market every five days and the inhabitants of the surrounding districts and mountains gather in their colorful costumes to sell vegetables, herbs, baked articles, tobacco and all sorts of homemade goods and who seldom return home without looking at, or even buying a few rubies. One must also mention the waterworks and sewage arrangements, which work very well, and a very old-fashioned electricity plant which sells its electricity (220V) during the day to the mines and only after 6 pm to the townspeople, so that one can only then use the electric light. It is then used so much that the voltage falls from 220V to 110, so that one can hardly read. The foreign visitor is well advised to take a torch along together with a sufficient supply of batteries. There is no official waste disposal, so it is not surprising that there are often cases of malaria, dysentery and typhoid. The visitor must be careful in every respect. Apart from various nature-cures and quacks, there are also a few good doctors in Mogok, but hospitals, old people’s homes and orphanages are not necessary since all these services are given by the family. There is always much life in the streets. Most goods are still transported on a shoulder-yoke or by ox-cart. There are many bicycles, and a few cars and vans. The riche mine owners have land-rovers, and there are various jeeps which are used as taxis to which transport people to the surrounding villages.
Although the whole district is only a few square miles and Mogok itself only a small town, there must be about 20000 people living in the district. The inhabitants are very mixed: apart from Burmese, there are Ghurkas, Hindus, Chinese and the romantic looking people from the Schan tribe. On each side of the street, in market places, in front of the tea houses and bazaars, there are small groups of squatting women showing each other small brass bowls with rubies. One soon has the impression that the whole population from the earliest youth to the oldest age is involved in the prospecting, production and sale of rubies, whether as a mine worker, mine owner, gem merchant, polisher, host or tradesman. The people are very friendly, helpful and open: the few that speak a foreign language like to talk to visitors.
The famous ruby mines are secondary deposits, that is, they have been brought down into the valley from decomposed primary deposits. Such alluvial deposits are found in most of the smaller and larger valleys of the district, and everywhere there is prospecting for rubies. Mogok lies in the lower part of a larger valley on what used to be the most profitable deposits. When the population realized this, they moved their township to the lower part of the hills so that they could mine the rubies in the valley. When there were no rubies, the craters which were formed by the mining operations filled with water, forming the lovely Mogok Lake, which today beautifies the valley. In the neighboring valleys the yellow clay is full of holes, and looks like a volcanic field of craters.
Prospecting and mining licenses are only given to Burmese. The owner who wants to open a small mine registers his intention with the district officer, who examines the claim. Depending on the size of the mine, the owner pays several hundred Kyats (1 Kyat = 1s. 6d) for the license. The license for a so-called machine-mine is about 1000 Kyats. The license cannot buy the land, which is only rented from the state for mining purposes. When mining operations are finished it is not necessary to fill in the craters and holes, contrary to practice in Ceylon. This is a defect in the law and leaves the valleys full of holes and unsuitable for agricultural purposes. For each employee the mine owner pays a monthly license fee of 10 Kyats and as a receipt obtains a small oval disc, which each miner must wear to facilitate inspection. Most mining is still done by hand with the help of water—without the local water supplies the mining could not have developed as it has.
Most of the stones are found in open-cast mines. The small narrow holes are widened with sticks and spades. The earth is put into woven bamboo baskets and lifted to the surface where it is emptied onto a heap. When the ruby-containing-the byons layer is reached, a byon heap is started, whence the earth is transported to the washing hole. Within a few weeks the small hole has become a mine of about 100 meters in diameter, perhaps reaching a depth of 20-30 meters, when the water level is reached. From a neighboring water tank water is hosed over the byon layers. The softened earth is pumped, either electrically or with a petrol engine, to a washing plant built from wood or stone and measuring perhaps four square meters and consisting of a basin which is about ½ -1 meter deep and from which there is a step-like arrangement of locks. Usually the earth is mined during the afternoon and then worked and washed the following morning, so that the gem-containing byon earth can settle during the night. In the morning clear water is pumped into the basin, washing away the top layer of waste earth, whilst the heavier gems settle in a series of boxes. During this time the washers stir up the deposit, so that it may be rinsed with water and carried away to a lower lock. Starting at the top the washers scoop some of the deposit up with their hands and shake it in a rough wire-mesh sieve to get rid of the large stones, the finer and medium deposit is then put into a shallow basket, from which the so-called therbat is put on the sorting table. The sorter, who in the case of small mines is the same man as the owner, combs through the therbat with a wooden comb and picks out the rubies. Just as the washing of the deposit below the last lock is free to everybody, so friends and relatives look through the waste from the sorting table either without remuneration or against a small fee. In this way all the innumerable small rubies which are used for adorning pieces of jewelry are won.
About 10 km west of Mogok, in the small township of Kathe and Kyatpyin, the valley is very dry and water not abundant and thus a new method of mining has developed. Parallel to each other long narrow trenches are dug, which are often connected under the surface by horizontal channels. These workings are usually co-owned by three to five men. At the opening of the shaft one or two winches are erected which help to bring to the surface the baskets which have been filled by a miner with the gem-containing earth or byon. The last man carries the basket either to the slack heap or the byon heap, which grows during the dry months from October to the end of April, and then is washed and worked during the summer monsoon season. Characteristic of the whole district is that there are no specially rich localities, but the precious stones can be found anywhere or everywhere, in a brook, in a rice field or in a mine. Ruby is the most looked for stone, but not the most common gem; there is one ruby found to every five spinels. There are fields which yield mainly rubies, other spinels, or moonstones or sapphires, and it has been known that certain mines produce certain colors, but in one basket of byon all types of unusual gems can be found. For the gem collector and gemologist the mines of Mogok are a real paradise, for apart from rubies, spinels, sapphires, moonstones and peridots, which are found in quantities, one also finds almandine garnets, amethysts, beryls, chrysoberyls, spessartites, topazes, tourmalines, zircons and citrines and mentioning some rare gems the following have been found as well: amblygonite, blue apatite, danburite, diopside, disthene, enstatite, violet fluorite, fibrolite, iolite, kornerupine, scapolite, titanite and others. The inhabitants of the districts know very little of these various gem types, and it is not surprising that one is often offered these stones under a wrong name. For instance, pink scapolite is known as pink moonstone and every yellow to brown stone as topaz. But if one knows anything about these stones, and in addition even possesses a refractometer, one can enrich a collection with many beautiful and rare specimens. There is a trade with rough rubies everywhere, along the mines, along the streets, in the bazaars, in the market places, in the backyards, and, of course, in the houses of the mine owners and gem dealers. Because there are always people looking on, a sign language using the fingers has been developed, with which one can express all numerals. Offers and acceptances are communicated under a cloth or in the wide sleeves of the engyis worn by the natives, so that none of the onlookers and strangers are any the wiser.
A large part of the gems found in Mogok and surrounding district are cut locally. Taking into account the very primitive grinding wheels the quality of the produced goods is fairly good, and quite usable according to Western standard. Depending on the resulting style the cutter chooses his tools and his method. Small stones, which are made into small cabochons, are usually worked by children and young girls. The rough stones are fixed onto a bamboo stick; five to ten of these sticks are held in each hand, then held onto a horizontally rotating grinding wheel. It is most instructive and enjoyable to watch how the hands lead the sticks on the wheel and how a few minutes later a number of cabochons are produced.
Large cabochons and star stones are produced by men who use special grinding boards with a carborundum covering; these boards have grooves of various widths in them which are also covered with various grades of carborundum. The rough stones are again fixed on bamboo sticks, which are pushed forwards and backwards in these grooves using finer and finer carborundum until the finished cabochons show a smooth highly polished surface.
The smaller facets are made by young boys, girls and women. The stones are fixed in a simple dop and the first facets are ground roughly on a carborundum board. After they have received their first rough shape they are fixed again onto sticks which can be held in a simple dop. The facets are then cut and polished on horizontally rotating grinding wheels, and from time to time checked by eye to ensure that they are even.
The large faceted stones are produced by a similar method, but only older and experienced cutters are allowed to make them. The advice of these cutters is welcomed by owners and dealers alike. The grinding wheels are rotated with the feet by a sort of treadle arrangement, as the old-fashioned electricity plant is not powerful enough to work all the wheels. Special large crystals are sometimes sawn before being cut and polished. In the whole of the district there is only one specialist who does this; he uses a machine which looks similar to an old sewing machine. It has a horizontal spindle on which a diamond sawing wheel is rotated by a foot pedal. Although the tools of their trade are primitive, most cutters are masters of their craft and know how to obtain the best results from an irregularly colored stone, or how to place inclusions or cracks in the stone into a position where it is extremely difficult to see them. Often stones with cracks are put into peanut oil so that cracks become invisible. It is also amazing how the Mogok cutters produce stones with even facets and regularity of geometrical planes. All these points show that their technical knowledge is greater than that of the Ceylonese cutters.
The buying of gems in Mogok is a time consuming but very interesting business, which needs absolute concentration and denial of western habits. It takes a long time for one to meet the people who sell the goods one wishes to buy. Once one has found them it needs a lot of patience until the stones are shown. Of the thousands of stones which are shown, only a few are of really good gem quality. Doubtless the families keep the very best stones to themselves and evens in Burma have shown the wisdom of this. But now and then a very fine gem is offered for sale. When the author was in Mogok, only after days of bargaining did the most important dealers show him a really good ruby or sapphire. The author was thus very impressed by the rarity and value of the finest gems. Most dealers show many lots of smaller and medium as well as a few larger rubies, but these lots are only shown one at a time, and much time and patience is needed to look through them all and wait for the appearance of better stones. The deal is never finalized without the wife giving her consent. The women of Mogok not only wear the jewels, they are also important in the mining, production and trade. In fact, the female gem merchants in Mogok are much tougher than the men and understand the fine qualities especially well.
The unit of weight is not the carat, but the Burmese rattie (1rt = 0.90 cts). The price of fine rubies has risen very sharply during the last 15 years. This has been caused not only by the increase in rarity, but also by the purchases of Indian merchants who pay too high a price for the rubies, as they earn some money on the transaction of the rupee-Kyat exchange. The inflationary and political uncertainities in Burma also play a part. The Burmese government is nationalizing all industries and has now also forbidden private businesses such as gem mining and dealing. The gem production is guarded by the army and all gems have to be sold to the Petrol and Mineral Development Corporation. The PMDC has now tried to sell the gems on the western markets, but was unsuccessful because of the low quality offered. During the first half of last December 180 gem dealers from 25 countries were invited to an officially organized sale, but most of these visitors were disappointed because of the poor quality offered to them. Many did not purchase anything as the poor qualities cannot be resold on the western markets. It seems a pity that most important gem producing countries have made free trading so difficult. For these countries the loss is usually only a few percent, while the loss in the free world is quite noticeable. These circumstances do not help to make the gems any cheaper, and every jeweler who has a few fine specimens is proud of them and knows how to treasure them.
Problems In Burma
2007: What a clever way to learn about gemstone pricing!
(via Journal of Gemmology, Vol.IX, No.10, April, 1965)
One way of obtaining a valuation of gems is reported in the February 1965 Lapidary Journal. An extract says:
Recently the present Burmese government, which is completely Communistic in its national policies, held a purported auction sale of seized gems in Rangoon from 1st December to 12th December. Supposedly the ordinary passport and visa regulations were relaxed for this purpose in order to attract foreign gem experts. The sale, it was said, was meant only for gem dealers and stone sellers.
Reliable persons who were inveigled to attend from outside Burma have now returned disappointed and report that the whole things was fake. The government only wanted to get a free appraisal of the gems from gem experts and dealers through written bids on each item of gemstones. This seems to be the only purpose of such a fake sale. Persons who made offers in writing were answered by slips under their hotel room doors stating that the gems they bid on were not for sale. Many persons complained about losing their valuable time and their own transportation money in this deal.
It is widely known that the gem mines of Burma have been nationalized, that is, seized by the Communistic dominated government authorities and that all former owners have been dispossessed, particularly and especially the Chinese who owned the principal gem mines in the ruby district of Mogok and in the jadeite regions of Upper Burma.
(via Journal of Gemmology, Vol.IX, No.10, April, 1965)
One way of obtaining a valuation of gems is reported in the February 1965 Lapidary Journal. An extract says:
Recently the present Burmese government, which is completely Communistic in its national policies, held a purported auction sale of seized gems in Rangoon from 1st December to 12th December. Supposedly the ordinary passport and visa regulations were relaxed for this purpose in order to attract foreign gem experts. The sale, it was said, was meant only for gem dealers and stone sellers.
Reliable persons who were inveigled to attend from outside Burma have now returned disappointed and report that the whole things was fake. The government only wanted to get a free appraisal of the gems from gem experts and dealers through written bids on each item of gemstones. This seems to be the only purpose of such a fake sale. Persons who made offers in writing were answered by slips under their hotel room doors stating that the gems they bid on were not for sale. Many persons complained about losing their valuable time and their own transportation money in this deal.
It is widely known that the gem mines of Burma have been nationalized, that is, seized by the Communistic dominated government authorities and that all former owners have been dispossessed, particularly and especially the Chinese who owned the principal gem mines in the ruby district of Mogok and in the jadeite regions of Upper Burma.
New Fund Will Add Greater Liquidity to the Multi-Million Dollar Stones Market
Chaim Even-Zohar writes about liquidity crunch in the diamond industry + capital raising efforts via derivatives, futures markets, securitization and hedge funds to other schemes + commodity investment management firm and Swiss-based Diapason + the funds concept of aiming at the high end of the market + other viewpoints @ http://www.idexonline.com/portal_FullEditorial.asp
Light Generates Electricity
(via National Geographic Magazine) Light generates electricity with the aid of crystals, a boon to camera fans and space scientists. When sunlight strikes the crystalline selenium in a light meter or the silicon solar cells on a satellite, electrons in the crystals become activated, providing the current that powers the meter and satellite.
Friday, June 29, 2007
The Art Of Failure
Malcolm Gladwell writes about performance studies + why some people choke and others panic @ http://www.gladwell.com/2000/2000_08_21_a_choking.htm
Threads: Their Types And Some Of Their Characters
(via The Journal of Gemmology, Vol 12, No.7, July 1971) Robert Webster writes:
For some time it has been the writer’s intention to consider some aspects of the nature of threads used to string pearls and beads into necklets, for the subject, which one might readily admit is not gemology proper, does have some importance in answering questions sometimes posed to a laboratory.
The reason which has prompted further investigation into this sphere devolved from some remarks made by the late Dr V B Meen, of Canada, after the writer had read a paper on damage to gemstones at the XIIIth International Gemmological Conference held at Brussels in 1970. During this talk the blackening of some cultured cultured pearls by the action of cosmetic creams was mentioned.
Dr Meen asked if any attention had been paid to the type of thread which had been used in stringing the pearls in the case mentioned, as some types of thread were more prone to attract grease than others. It was possible to show that in the records of this case there was a note to the effect that the string did not appear to be normal, but that this aspect was not pursued.
There may be other problems, too, where some information on the nature of the string used in threading beads may well be needed. This article is an attempt to give a short survey and to provide a basis for any future investigation. It will be readily seen that any full-scale investigation on the types and characters of threads would be a long-term project, but one which might well be worthwhile.
According to Walls threads, the more scientific name being fibres, can be classified into four groups as follows:
1. Animal hairs such as wool, mohair (Angora goat), camel, none of which have any place in the present study.
2. Vegetable fibres, which are divided into two groups. (a) Seed hairs, such as cotton and kapok, cotton being the only one which needs consideration here. (b) Bast and structural fibres; these are exemplified by flax (linen), jute, hemp and sisal. Only flax is of interest.
3. Fibres produced by the solidification of a liquid extruded through a fine orifice; these are again subdivided into sub-groups:-
(a) Natural, of which silk is the only important member.
(b) Artificial (man-made); there are two well defined groups:-
(i) Those made from animal or vegetable raw materials, such as regenerated cellulose (Rayon); cellulose esters, usually acetate (Tricel, Arnel, Trilon); alginates (from seaweed); regenerated proteins (casein) and others.
(ii) Purely synthetic fibres: such as polyolefines (polyethylene, etc); polyamides (Nylon, Brilon); polyesters (e.g. Terylene—Dacron in the United States of America—a polyethylene terephthalate); acrylonitrile polymers (Orlon, Acrilan, Courtelle, etc); vinyl chloride and vinylidene chloride polymers (Vinyon, Saran, and others).
4. Miscellaneous fibres; such fibres are natural mineral fibres (asbestos) and fibres of glass, metal, etc. which have no place in this study.
Of these numerous fibres, most of which are used in the textile industry, the only ones which need to be discussed are silk, cotton, linen, and some of the artificial fibres, particularly Nylon.
Silk
The most important fibre used for pearl stringing, silk is produced by the caterpillar of the moth Bombyx mori, which, when fully grown, spins a cocoon with a secretion produced by the caterpillar from a pair of tubular spinning glands. Each of these glands produces a single fibre, which is at first in a fluid condition.
These two fibres are then, by muscular action, and possibly aided by another secretion, formed into a single thread. This is silk, an albumoid, and the fibres normally receive certain cleaning treatments before being spun and woven into fabrics.
When a flame is applied to the end of a silk thread it burns, but does not readily flame, and the thread forms a shriveled blob. The flame does not tend to travel along the thread and is quickly extinguished. Under the microscope the threads are seen to be more or less structureless cylindrical rods which at places may flatten or bulge out. The fluorescence varies considerably due, as mentioned by Radley and Grant, to the fact that dressing agents, oils and dyestuffs, often completely alter the color of the fluorescence, and these writers also state that small traces of fluorescent dyestuffs added as brightening agents may produce complicating effects in ultraviolet light. Fluorescence can have scant discriminative value in the detection of the fibres themselves.
Cotton
Threads of cotton are not normally used for pearl stringing but some mention is included in this survey for there is reason to believe that they have been used for such a purpose, and, further, they are certainly used for stringing necklets of amber, coral, jet and some ornamental stones, such as malachite and rhodonite. Star sylko or Clark’s anchor stranded embroidery silks are often used for stringing such necklets.
The most important of the vegetable fibres, cotton, consists of white or yellowish-colored fibres which are obtained from the seeds of various species of the genus Gossypium of the order Malvaccae. Well bleached cotton is said to be nearly pure cellulose.
When a flame is applied to cotton threads they readily burn with the flame traveling along the thread leaving very little ash. On extinction of the flame the glowing embers emit a smell of burnt wood. When fibres of raw cotton are examined under the microscope the general appearance resembles that of a wrinkled, twisted irregular ribbon which may be likened to an exhausted rubber tubing. After treatment, such as mercerizing, which imparts a luster to the cotton so that it resembles to some extent silk, the typical appearance of the threads may not be so apparent under magnification.
Linen
The name is derived from the flax plant Linum usitatissimum, which is pulled just after flowering. The linen fibre, being the first layer under the epidermis of the stalk is separated from the rest of the stalk by retting in stagnant or running water. Following this the mucilaginous substances contained in the flax are removed by suitable treatments.
Like cotton, linen burns fairly readily with, on extinction, a smell of smoldering wood. Examined under the microscope the central canal is not so marked as in cotton and the fibre has notches at irregular intervals, and, further, may show diagonal striations. Linen lacks the convolutions shown by cotton fibres.
Artificial fibres
The beginning of the artificial fibre industry began with the work of Count Hilaire de Chardonnet of France during the 1880’s, although as early as 1665 the idea of making artificial silk was mooted by Robert Hooke. Chardonnet’s silk was nitrated cellulose, a type of celluloid, and was far too inflammable and, indeed, the sale of this silk was eventually banned in France.
The next advance in the production of artificial silks was due to the work of C F Cross and E J Bevan, who produced the rayons. These fibres were and are produced by regenerating cellulose. Plant cellulose, such as cotton linters, wood-pulp, are chemically dissolved and then regenerated and extruded through a diaphragm pierced with very fine orifices called spinnerette. Such regenerated cellulose fibres are Viscose rayon, cuprammonium rayon, and acetate rayon, but these fibres have little importance in this discussion.
The most important of the man-made fibres for this study is the super-polyamide called nylon, the production of which was the outcome of researches carried out by the American plastics chemist Carothers, aided by some of his colleagues. Made from hydrocarbons obtained from coal, and from ammonia, nylon, of which there are at least three types, is said to be twice as strong as silk and to be more elastic. It is probably due to this latter effect that nylon is not favored for pearl stringing as it does not knot well is inclined to stretch. There are two kinds of nylon cord which may be purchased for pearl and bead stringing. The first is made up of twisted fibres and resembles the true pearl silk, while the other, more used for beads than pearls, consists of a single strand, like a flexible rod. There is a variation of this latter type which is wound round with a spiral of fine metal wire and presumably used for heavy beads. If the single strand nylon cord is used for pearls or lightweight beads the necklet tends to bow and does not hand at all well.
Nylon melts before burning, producing a sticky blob which follows the flame traveling along the string. This blob of molten material, if dropped on to the skin, burns like hot fat. The flame of burning nylon is, however, readily extinguished. Nylons, like most of the other man-made fibres, are usually assumed to be structureless internally, but microscopical examination has shown that there appear to be masses of fine bubbles oriented parallel to the length of the fibre. This phenomenon seems to be more prominent in the case of nylon and this may be accounted for as nylon is extruded from a molten mass and not from a liquid which is expelled through the spinnerettes into a coagulating bath which solidifies the fibres.
In order to ascertain the probability of differential absorption of grease by various fibres a series of experiments were undertaken. A frame was constructed consisting of a length of channel aluminum, bored with eight small holes through both sides, which was screwed down to a suitable baseboard. The metal channel, intended to carry the grease, was closed at each end by aluminum angle plates. A series of different threads were then threaded through the holes in the channel and anchored so that they were fixed at the outer face of the channel. The threads then passed across the channel and across the baseboard for a distance of some 12 centimeters, where the ends were anchored to a fixed wooden strip by the aid of drawing pins. Suitable lettered labels were stuck down on the baseboard in order to identify the strands.
It was considered that suitable grease would be a cosmetic cream and Pond’s cold cream was used. To ascertain if the grease traveled along the string a small quantity of the chemical rhodamine was mixed with the cold cream, the notion being that it would not only give color to the but would show up under ultraviolet light, for rhodamine is highly fluorescent and glows with an orange or reddish brown light. During the experiment the frame was kept in a glass-topped box.
The strings used in the first experiment were as follows:
(a) Silk (dyed brown)
(b) Pearl silk
(c) Sylko mercerized cotton
(d) Linen thread
(e) Terylene thread
(f) Nylon (single thread)
(g) Spun nylon pearl silk (Nylcord)
(h) Clark’s anchor stranded embroidery cotton
The result observed after the grease had been placed in the channel was striking in that within an hour the grease had traveled down some of the threads, admittedly not very far but with significant differences. Strangely the seepage seemed to stop at these points and there was little further increase even after a week. The distances the grease, which colored the strings, had traveled along the strings were then measured, giving the following results:
(a) Dyed silk: no apparent effect
(b) Pearl silk: very weak seepage of about 1.5 mm
(c) Sylko mercerized cotton: 5mm
(d) Linen: 2mm
(e) Terylene: 4mm
(f) Nylon single cord: no effect
(g) Twisted nylon (Nylcord): 11mm
(h) Embroidery cotton: 3mm
The frame was then unstrung and the grease removed and kept, and the frame itself thoroughly cleaned and restrung with different threads as under:
(a) A fine tacking cotton
(b) Brown linen thread
(c) Terylene, same type of thread as in (e) in first run
(d) Pearl stringing silk. A different source from (b) above
(e) Pure silk (yellow dyed Regal)
(f) Polyethylene thread (blue dyed)
(g) Terylene (Coat’s white)
(h) Embroidery silk (cotton) as in (h) above
The cold cream plus rhodamine, which was removed from the channel after the first run, was then mixed with as much again of the cold cream but no more rhodamine added. Thus the concentration of rhodamine was only half that of the previous mixture.
After some hours the frame and threads were examined, but the results appeared to be disappointing, mainly because the lower concentration of rhodamine did not strikingly color the threads, and the fluorescence effects were masked by the strong whitish glow emitted by the threads themselves. However, some trace of differential seepage was apparent.
There was always the question of how much body heat would affect the mobility of grease in the case of a necklet worn for some time around the neck. To test this, the frame was removed from the glass-topped box and placed on a warm print dryer. This print dryer gave off much more heat than the heat given off by a human body, and, hence, the results obtained would be expected to be much more rapid, as, indeed they seemed to be as the following shows:
(a) Cotton thread: diffuse staining decreasing in intensity up to 5 to 6 cms
(b) Linen: a little staining up to 2 to 3 mm
(c) Terylene: slight tinting for practically the full length of the string
(d) Pearl silk: very slight staining for 3 to 4 cms
(e) Yellow dyed pure silk: very slight staining
(f) Polyethylene: color of the dyed thread precluded much in the way of observation or by fluorescence
(g) Terylene: weak staining for a considerable distance, and in fact seemed to behave rather like (c)
(h) Cotton embroidery silk: staining for about 15 mm
Note: the very slight staining of the Terylenes (c) and (g) could only be identified by comparison with thread taken from the original reels.
In conclusion, it may be said that the experiments have shown that there is some justification for the suggestion that there is differential absorption and percolation of grease along fibres of different natures. However, much more information is required and far more experimentation needs to be carried out on a greater number of kinds of fibres for a really full study of the subject. It seems apparent that twisted fibres tend to carry grease more readily than single strand material, as exemplified by the nylon samples tested. This was rather to be expected and most probably due to the greater possibility of capillary attraction between the threads.
Most of the threads carried grease for upwards of two millimeters, and as the nacreous shell of a cultured pearl is seldom more than a millimeter thick, it is clear that the grease would reach the discontinuation layer between the skin and the bead of the cultured pearl and tend to travel along it, as indeed, was found to have happened in the case mentioned at the beginning of this article.
What is further to be considered is that the experiments were carried out with static threads on a frame. There is movement of the beads on a necklet when it is worn and this would assist the grease to seep along the string. What does seem to be proved by the experiments is that silk is the best material to use in stringing natural and cultured pearls and to use other types of thread may well lead to trouble for the jeweler.
For some time it has been the writer’s intention to consider some aspects of the nature of threads used to string pearls and beads into necklets, for the subject, which one might readily admit is not gemology proper, does have some importance in answering questions sometimes posed to a laboratory.
The reason which has prompted further investigation into this sphere devolved from some remarks made by the late Dr V B Meen, of Canada, after the writer had read a paper on damage to gemstones at the XIIIth International Gemmological Conference held at Brussels in 1970. During this talk the blackening of some cultured cultured pearls by the action of cosmetic creams was mentioned.
Dr Meen asked if any attention had been paid to the type of thread which had been used in stringing the pearls in the case mentioned, as some types of thread were more prone to attract grease than others. It was possible to show that in the records of this case there was a note to the effect that the string did not appear to be normal, but that this aspect was not pursued.
There may be other problems, too, where some information on the nature of the string used in threading beads may well be needed. This article is an attempt to give a short survey and to provide a basis for any future investigation. It will be readily seen that any full-scale investigation on the types and characters of threads would be a long-term project, but one which might well be worthwhile.
According to Walls threads, the more scientific name being fibres, can be classified into four groups as follows:
1. Animal hairs such as wool, mohair (Angora goat), camel, none of which have any place in the present study.
2. Vegetable fibres, which are divided into two groups. (a) Seed hairs, such as cotton and kapok, cotton being the only one which needs consideration here. (b) Bast and structural fibres; these are exemplified by flax (linen), jute, hemp and sisal. Only flax is of interest.
3. Fibres produced by the solidification of a liquid extruded through a fine orifice; these are again subdivided into sub-groups:-
(a) Natural, of which silk is the only important member.
(b) Artificial (man-made); there are two well defined groups:-
(i) Those made from animal or vegetable raw materials, such as regenerated cellulose (Rayon); cellulose esters, usually acetate (Tricel, Arnel, Trilon); alginates (from seaweed); regenerated proteins (casein) and others.
(ii) Purely synthetic fibres: such as polyolefines (polyethylene, etc); polyamides (Nylon, Brilon); polyesters (e.g. Terylene—Dacron in the United States of America—a polyethylene terephthalate); acrylonitrile polymers (Orlon, Acrilan, Courtelle, etc); vinyl chloride and vinylidene chloride polymers (Vinyon, Saran, and others).
4. Miscellaneous fibres; such fibres are natural mineral fibres (asbestos) and fibres of glass, metal, etc. which have no place in this study.
Of these numerous fibres, most of which are used in the textile industry, the only ones which need to be discussed are silk, cotton, linen, and some of the artificial fibres, particularly Nylon.
Silk
The most important fibre used for pearl stringing, silk is produced by the caterpillar of the moth Bombyx mori, which, when fully grown, spins a cocoon with a secretion produced by the caterpillar from a pair of tubular spinning glands. Each of these glands produces a single fibre, which is at first in a fluid condition.
These two fibres are then, by muscular action, and possibly aided by another secretion, formed into a single thread. This is silk, an albumoid, and the fibres normally receive certain cleaning treatments before being spun and woven into fabrics.
When a flame is applied to the end of a silk thread it burns, but does not readily flame, and the thread forms a shriveled blob. The flame does not tend to travel along the thread and is quickly extinguished. Under the microscope the threads are seen to be more or less structureless cylindrical rods which at places may flatten or bulge out. The fluorescence varies considerably due, as mentioned by Radley and Grant, to the fact that dressing agents, oils and dyestuffs, often completely alter the color of the fluorescence, and these writers also state that small traces of fluorescent dyestuffs added as brightening agents may produce complicating effects in ultraviolet light. Fluorescence can have scant discriminative value in the detection of the fibres themselves.
Cotton
Threads of cotton are not normally used for pearl stringing but some mention is included in this survey for there is reason to believe that they have been used for such a purpose, and, further, they are certainly used for stringing necklets of amber, coral, jet and some ornamental stones, such as malachite and rhodonite. Star sylko or Clark’s anchor stranded embroidery silks are often used for stringing such necklets.
The most important of the vegetable fibres, cotton, consists of white or yellowish-colored fibres which are obtained from the seeds of various species of the genus Gossypium of the order Malvaccae. Well bleached cotton is said to be nearly pure cellulose.
When a flame is applied to cotton threads they readily burn with the flame traveling along the thread leaving very little ash. On extinction of the flame the glowing embers emit a smell of burnt wood. When fibres of raw cotton are examined under the microscope the general appearance resembles that of a wrinkled, twisted irregular ribbon which may be likened to an exhausted rubber tubing. After treatment, such as mercerizing, which imparts a luster to the cotton so that it resembles to some extent silk, the typical appearance of the threads may not be so apparent under magnification.
Linen
The name is derived from the flax plant Linum usitatissimum, which is pulled just after flowering. The linen fibre, being the first layer under the epidermis of the stalk is separated from the rest of the stalk by retting in stagnant or running water. Following this the mucilaginous substances contained in the flax are removed by suitable treatments.
Like cotton, linen burns fairly readily with, on extinction, a smell of smoldering wood. Examined under the microscope the central canal is not so marked as in cotton and the fibre has notches at irregular intervals, and, further, may show diagonal striations. Linen lacks the convolutions shown by cotton fibres.
Artificial fibres
The beginning of the artificial fibre industry began with the work of Count Hilaire de Chardonnet of France during the 1880’s, although as early as 1665 the idea of making artificial silk was mooted by Robert Hooke. Chardonnet’s silk was nitrated cellulose, a type of celluloid, and was far too inflammable and, indeed, the sale of this silk was eventually banned in France.
The next advance in the production of artificial silks was due to the work of C F Cross and E J Bevan, who produced the rayons. These fibres were and are produced by regenerating cellulose. Plant cellulose, such as cotton linters, wood-pulp, are chemically dissolved and then regenerated and extruded through a diaphragm pierced with very fine orifices called spinnerette. Such regenerated cellulose fibres are Viscose rayon, cuprammonium rayon, and acetate rayon, but these fibres have little importance in this discussion.
The most important of the man-made fibres for this study is the super-polyamide called nylon, the production of which was the outcome of researches carried out by the American plastics chemist Carothers, aided by some of his colleagues. Made from hydrocarbons obtained from coal, and from ammonia, nylon, of which there are at least three types, is said to be twice as strong as silk and to be more elastic. It is probably due to this latter effect that nylon is not favored for pearl stringing as it does not knot well is inclined to stretch. There are two kinds of nylon cord which may be purchased for pearl and bead stringing. The first is made up of twisted fibres and resembles the true pearl silk, while the other, more used for beads than pearls, consists of a single strand, like a flexible rod. There is a variation of this latter type which is wound round with a spiral of fine metal wire and presumably used for heavy beads. If the single strand nylon cord is used for pearls or lightweight beads the necklet tends to bow and does not hand at all well.
Nylon melts before burning, producing a sticky blob which follows the flame traveling along the string. This blob of molten material, if dropped on to the skin, burns like hot fat. The flame of burning nylon is, however, readily extinguished. Nylons, like most of the other man-made fibres, are usually assumed to be structureless internally, but microscopical examination has shown that there appear to be masses of fine bubbles oriented parallel to the length of the fibre. This phenomenon seems to be more prominent in the case of nylon and this may be accounted for as nylon is extruded from a molten mass and not from a liquid which is expelled through the spinnerettes into a coagulating bath which solidifies the fibres.
In order to ascertain the probability of differential absorption of grease by various fibres a series of experiments were undertaken. A frame was constructed consisting of a length of channel aluminum, bored with eight small holes through both sides, which was screwed down to a suitable baseboard. The metal channel, intended to carry the grease, was closed at each end by aluminum angle plates. A series of different threads were then threaded through the holes in the channel and anchored so that they were fixed at the outer face of the channel. The threads then passed across the channel and across the baseboard for a distance of some 12 centimeters, where the ends were anchored to a fixed wooden strip by the aid of drawing pins. Suitable lettered labels were stuck down on the baseboard in order to identify the strands.
It was considered that suitable grease would be a cosmetic cream and Pond’s cold cream was used. To ascertain if the grease traveled along the string a small quantity of the chemical rhodamine was mixed with the cold cream, the notion being that it would not only give color to the but would show up under ultraviolet light, for rhodamine is highly fluorescent and glows with an orange or reddish brown light. During the experiment the frame was kept in a glass-topped box.
The strings used in the first experiment were as follows:
(a) Silk (dyed brown)
(b) Pearl silk
(c) Sylko mercerized cotton
(d) Linen thread
(e) Terylene thread
(f) Nylon (single thread)
(g) Spun nylon pearl silk (Nylcord)
(h) Clark’s anchor stranded embroidery cotton
The result observed after the grease had been placed in the channel was striking in that within an hour the grease had traveled down some of the threads, admittedly not very far but with significant differences. Strangely the seepage seemed to stop at these points and there was little further increase even after a week. The distances the grease, which colored the strings, had traveled along the strings were then measured, giving the following results:
(a) Dyed silk: no apparent effect
(b) Pearl silk: very weak seepage of about 1.5 mm
(c) Sylko mercerized cotton: 5mm
(d) Linen: 2mm
(e) Terylene: 4mm
(f) Nylon single cord: no effect
(g) Twisted nylon (Nylcord): 11mm
(h) Embroidery cotton: 3mm
The frame was then unstrung and the grease removed and kept, and the frame itself thoroughly cleaned and restrung with different threads as under:
(a) A fine tacking cotton
(b) Brown linen thread
(c) Terylene, same type of thread as in (e) in first run
(d) Pearl stringing silk. A different source from (b) above
(e) Pure silk (yellow dyed Regal)
(f) Polyethylene thread (blue dyed)
(g) Terylene (Coat’s white)
(h) Embroidery silk (cotton) as in (h) above
The cold cream plus rhodamine, which was removed from the channel after the first run, was then mixed with as much again of the cold cream but no more rhodamine added. Thus the concentration of rhodamine was only half that of the previous mixture.
After some hours the frame and threads were examined, but the results appeared to be disappointing, mainly because the lower concentration of rhodamine did not strikingly color the threads, and the fluorescence effects were masked by the strong whitish glow emitted by the threads themselves. However, some trace of differential seepage was apparent.
There was always the question of how much body heat would affect the mobility of grease in the case of a necklet worn for some time around the neck. To test this, the frame was removed from the glass-topped box and placed on a warm print dryer. This print dryer gave off much more heat than the heat given off by a human body, and, hence, the results obtained would be expected to be much more rapid, as, indeed they seemed to be as the following shows:
(a) Cotton thread: diffuse staining decreasing in intensity up to 5 to 6 cms
(b) Linen: a little staining up to 2 to 3 mm
(c) Terylene: slight tinting for practically the full length of the string
(d) Pearl silk: very slight staining for 3 to 4 cms
(e) Yellow dyed pure silk: very slight staining
(f) Polyethylene: color of the dyed thread precluded much in the way of observation or by fluorescence
(g) Terylene: weak staining for a considerable distance, and in fact seemed to behave rather like (c)
(h) Cotton embroidery silk: staining for about 15 mm
Note: the very slight staining of the Terylenes (c) and (g) could only be identified by comparison with thread taken from the original reels.
In conclusion, it may be said that the experiments have shown that there is some justification for the suggestion that there is differential absorption and percolation of grease along fibres of different natures. However, much more information is required and far more experimentation needs to be carried out on a greater number of kinds of fibres for a really full study of the subject. It seems apparent that twisted fibres tend to carry grease more readily than single strand material, as exemplified by the nylon samples tested. This was rather to be expected and most probably due to the greater possibility of capillary attraction between the threads.
Most of the threads carried grease for upwards of two millimeters, and as the nacreous shell of a cultured pearl is seldom more than a millimeter thick, it is clear that the grease would reach the discontinuation layer between the skin and the bead of the cultured pearl and tend to travel along it, as indeed, was found to have happened in the case mentioned at the beginning of this article.
What is further to be considered is that the experiments were carried out with static threads on a frame. There is movement of the beads on a necklet when it is worn and this would assist the grease to seep along the string. What does seem to be proved by the experiments is that silk is the best material to use in stringing natural and cultured pearls and to use other types of thread may well lead to trouble for the jeweler.
Paying The Price For Suffering Banking Discord
Chaim Even-Zohar writes about M Fabrikant & Sons + the bankers + risk-mitigation strategies of banks + other viewpoints @ http://www.idexonline.com/portal_FullEditorial.asp?TextSearch=&KeyMatch=0&id=26543
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