History & Technique from the Egyptians to the Present
By Guido Gregorietti
Chartwell Books, Inc
1979 ISBN 089009-231-1
Chartwell Books writes:
A jewel has many meanings. It is a work of art, an ornament denoting rank, a statement of dress, a treasure, a sign of power, an investment, an ethnic clue, an ostentation.
One of the most famous and dependable Parisian jewelers, whose base is in Place Vendome, makes it a professional rule never to reveal the identity of his customers. One exception was made, however, when the firm was put in charge of preparing the ceremonial crown for the Empress of Iran. It would have been difficult to keep it anonymous: 1469 diamonds, 36 rubies, as many emeralds and 105 pearls were mounted on the crown in Teheran, after a year’s work.
Why jewels are never enough to satisfy is a problem for anthropologists and psychologists to explain. A bouquet of 6000 diamonds was shown at the Great Exhibition of 1851 in London; perhaps satisfying enough? Between 1884 and 1917 the Tsar of Russia presented members of his family with fifty Easter eggs with surprises in them, created by the famous Faberge in enamel and precious stones.
If we pause to think of the quantity of jewels worked into gold dug up at Troy, in Mesopotamia, in Egypt and Peru, we see the ancients could compete favorably with modern craftsmen. Also—and a curious thing to have to admit with today’s technology—the ancients had techniques which no one since has known how to repeat.
The history of jewelry, too, has a certain amount of unknown meaning. It even sometimes has a superstitious aura of occult magic.
Guido Gregorietti’s narrative of the fabulous history of jewelry places it in context in the history of art, while interweaving many aspects of the evolution of culture.
About the author
Guido Gregorietti is the author of the Jewelry entry in the Encyclopedia Britannica, and was called upon to take part in judging the 1977 Diamond Award in New York.
Sunday, March 18, 2007
Saturday, March 17, 2007
(How to) Heating Zircon
(via Wahroongai News, Volume 33, Number 7, July 1999) Mark Liccini writes:
Here is how to heat zircon. You place them flawless……must be real clean or they will crack, and even then some may crack….in a (fire-clay) crucible with activated charcoal. This can be bought from any chemical supply company for about US$30 for a small container. Activated charcoal is the best to use, but there is another way to avoid using of reductive gas. Importantly, activated charcoal will work without creating any smoke. The other way is to put sugar in the crucible, but it starts to put out a lot of smoke when you get up to temperatures of 600°C or more. Although the smoking of sugar stops around 800°C, lots and lots of smoke will be generated. Boy! I mean a lot of smoke!
Then, you then must fill the crucible with zircon and seal the crucible. A good way is window screen and just a layer of plaster (plaster-of-Paris) over the top of the screen. Let it dry; then fill in any cracks after the plaster has dried. You then take the temperature of the crucible up slowly. The slower you go, less breakage will occur….all the way to 1000°C. Hold the temperature there for 2 hours or so. The controlled rise in temperature, depending on your furnace could take all day or longer. Following heating it can take 5-6 hours to cool the crucible down to cold (room temperature). Don’t open the door while the crucible and its contents are hot, or all will crack.
Now here are some tricks of the trade.
You will observe precisely in the bottom of a sealed crucible the best blues will be found. Near the top the heat treated zircons may be white. If you rotate the zircon rough imposition and repeat the heating and cooling cycle again, the white zircons will turn blue. If you overheat the zircons (and bleach them), you can do them again and they will come back blue. Even light blues done again will change to dark blues.
Now there is a trick to produce orange and red colors. You might obtain some oranges and red on the top of a sealed crucible. Indeed, when you first open a sealed crucible you will go crazy. The whole top will be covered with red and oranges. However, beware, for after a few minutes in the air all oranges and reds will revert to white and/or light blue—except a stone or two. These are stable reds and oranges. Now to ensure a high percentage of reds and oranges do the same heat treatment without sugar (or activated charcoal) and in an open crucible.
Note: With both heat treatment methods, you will get better results with a full crucible of zircon rough. Although I have never heat treated Cambodian zircons, I have run tonnage of Nigerian and some from Tanzania and Australia.
Here is how to heat zircon. You place them flawless……must be real clean or they will crack, and even then some may crack….in a (fire-clay) crucible with activated charcoal. This can be bought from any chemical supply company for about US$30 for a small container. Activated charcoal is the best to use, but there is another way to avoid using of reductive gas. Importantly, activated charcoal will work without creating any smoke. The other way is to put sugar in the crucible, but it starts to put out a lot of smoke when you get up to temperatures of 600°C or more. Although the smoking of sugar stops around 800°C, lots and lots of smoke will be generated. Boy! I mean a lot of smoke!
Then, you then must fill the crucible with zircon and seal the crucible. A good way is window screen and just a layer of plaster (plaster-of-Paris) over the top of the screen. Let it dry; then fill in any cracks after the plaster has dried. You then take the temperature of the crucible up slowly. The slower you go, less breakage will occur….all the way to 1000°C. Hold the temperature there for 2 hours or so. The controlled rise in temperature, depending on your furnace could take all day or longer. Following heating it can take 5-6 hours to cool the crucible down to cold (room temperature). Don’t open the door while the crucible and its contents are hot, or all will crack.
Now here are some tricks of the trade.
You will observe precisely in the bottom of a sealed crucible the best blues will be found. Near the top the heat treated zircons may be white. If you rotate the zircon rough imposition and repeat the heating and cooling cycle again, the white zircons will turn blue. If you overheat the zircons (and bleach them), you can do them again and they will come back blue. Even light blues done again will change to dark blues.
Now there is a trick to produce orange and red colors. You might obtain some oranges and red on the top of a sealed crucible. Indeed, when you first open a sealed crucible you will go crazy. The whole top will be covered with red and oranges. However, beware, for after a few minutes in the air all oranges and reds will revert to white and/or light blue—except a stone or two. These are stable reds and oranges. Now to ensure a high percentage of reds and oranges do the same heat treatment without sugar (or activated charcoal) and in an open crucible.
Note: With both heat treatment methods, you will get better results with a full crucible of zircon rough. Although I have never heat treated Cambodian zircons, I have run tonnage of Nigerian and some from Tanzania and Australia.
Gigi
Memorable quote (s) from the movie:
Gigi (Leslie Caron): I don't know what you want. You told Grandmama...
Gaston (Louis Jourdan): I know what I told your grandmother. We don't have to repeat it. Just tell me simply what you don't want... and tell me what you do want.
Gigi (Leslie Caron): Do you mean that?
Gaston (Louis Jourdan): Of course.
Gigi (Leslie Caron): You told Grandmama that you wanted to take care of me.
Gaston (Louis Jourdan): To take care of you beautifully.
Gigi (Leslie Caron): Beautifully. That is, if I like it. They've pounded into my head I'm backward for my age... but I know what all this means. To take care of me beautifully means I shall go away with you... and that I shall sleep in your bed.
Gaston (Louis Jourdan): Please, Gigi. I beg of you, you embarrass me.
Gigi (Leslie Caron): You weren't embarrassed to talk to Grandmama about it. And Grandmama wasn't embarrassed to talk to me about it. But I know more than she told me. To take care of me means that I shall have my photograph in the papers. That I shall go to the Riviera. To the races at Deauville. And when we fight, it will be in all the columns the next day. And then you'd give me up, as you did with InÈs des CÈvennes.
Gaston (Louis Jourdan): Who's been filling your head with all these old stories? How do you know about that?
Gigi (Leslie Caron): Why shouldn't I know? You're world famous. I know about the woman who stole from you; the Contessa who wanted to shoot you; the American who wanted to marry you. I know what everybody knows.
Gaston (Louis Jourdan): These aren't the things we have to talk about together. That's all in the past, over and done with.
Gigi (Leslie Caron): Yes, Gaston. Until it begins again.
Gigi (Leslie Caron): I don't know what you want. You told Grandmama...
Gaston (Louis Jourdan): I know what I told your grandmother. We don't have to repeat it. Just tell me simply what you don't want... and tell me what you do want.
Gigi (Leslie Caron): Do you mean that?
Gaston (Louis Jourdan): Of course.
Gigi (Leslie Caron): You told Grandmama that you wanted to take care of me.
Gaston (Louis Jourdan): To take care of you beautifully.
Gigi (Leslie Caron): Beautifully. That is, if I like it. They've pounded into my head I'm backward for my age... but I know what all this means. To take care of me beautifully means I shall go away with you... and that I shall sleep in your bed.
Gaston (Louis Jourdan): Please, Gigi. I beg of you, you embarrass me.
Gigi (Leslie Caron): You weren't embarrassed to talk to Grandmama about it. And Grandmama wasn't embarrassed to talk to me about it. But I know more than she told me. To take care of me means that I shall have my photograph in the papers. That I shall go to the Riviera. To the races at Deauville. And when we fight, it will be in all the columns the next day. And then you'd give me up, as you did with InÈs des CÈvennes.
Gaston (Louis Jourdan): Who's been filling your head with all these old stories? How do you know about that?
Gigi (Leslie Caron): Why shouldn't I know? You're world famous. I know about the woman who stole from you; the Contessa who wanted to shoot you; the American who wanted to marry you. I know what everybody knows.
Gaston (Louis Jourdan): These aren't the things we have to talk about together. That's all in the past, over and done with.
Gigi (Leslie Caron): Yes, Gaston. Until it begins again.
A Timely Warning: Pakistani Fakes
(Via Wahroongai News, Volume 33, Number 6, June 1999)
The letter reproduced below was first published in the January – February 1999 issue of The Mineralogical Record.
“I have recently returned from Northern Areas, Pakistan, where I encountered several sophisticated fake specimens. In fact, I am now the proud owner of several, having not recognized them at the time of the purchase. All of the fakes were apparently made of material from Chumar Bakhoor Nagar (the source of the specimens of aquamarine crystals on muscovite crystals). One such specimen consisting of a fairly nice green fluorite octahedron with aquamarine was obtained in the bazaar of Karimabad, Hunza. The fluorite and aquamarine is surrounded by a band of iron stained fine-grained material. This became obvious when the specimen was cleaned. Another consisted of a tabular beryl with an aquamarine crystal which, on examination, could have not grown where it was sited. This specimen fell apart, allowing me to salvage the nice tabular beryl. Another was a specimen of a pink apatite crystal in a matrix of quartz and muscovite. These last two were obtained from the site on the Karakoram Highway known as Rakaposhi Main Point. Get only photos of Rakaposhi here—the summit is 19000 feet above and seven miles horizontally from you. At last fake is really good, consisting of a fine aquamarine crystals on muscovite obtained from the hotel shop at the Riveria Hotel, Gilgit. It should be noted that some of the dealers volunteered the information that certain specimens were fake. It is likely that the dealers from whom I got some of the fakes were also conned by their sources. So all material allegedly from Chumar Bhakoor Nagar should be examined with care.”
This letter clearly reveals that even the experts get conned by the locals of the Hunza Valley. So beware.
The letter reproduced below was first published in the January – February 1999 issue of The Mineralogical Record.
“I have recently returned from Northern Areas, Pakistan, where I encountered several sophisticated fake specimens. In fact, I am now the proud owner of several, having not recognized them at the time of the purchase. All of the fakes were apparently made of material from Chumar Bakhoor Nagar (the source of the specimens of aquamarine crystals on muscovite crystals). One such specimen consisting of a fairly nice green fluorite octahedron with aquamarine was obtained in the bazaar of Karimabad, Hunza. The fluorite and aquamarine is surrounded by a band of iron stained fine-grained material. This became obvious when the specimen was cleaned. Another consisted of a tabular beryl with an aquamarine crystal which, on examination, could have not grown where it was sited. This specimen fell apart, allowing me to salvage the nice tabular beryl. Another was a specimen of a pink apatite crystal in a matrix of quartz and muscovite. These last two were obtained from the site on the Karakoram Highway known as Rakaposhi Main Point. Get only photos of Rakaposhi here—the summit is 19000 feet above and seven miles horizontally from you. At last fake is really good, consisting of a fine aquamarine crystals on muscovite obtained from the hotel shop at the Riveria Hotel, Gilgit. It should be noted that some of the dealers volunteered the information that certain specimens were fake. It is likely that the dealers from whom I got some of the fakes were also conned by their sources. So all material allegedly from Chumar Bhakoor Nagar should be examined with care.”
This letter clearly reveals that even the experts get conned by the locals of the Hunza Valley. So beware.
A Rare Biological Gem Material: Aromatic Resin (Myrrh) Necklace
(via Wahroongai News, Volume 30, May 1996) Grahame Brown writes:
Myrrh, one of the three gifts to the baby Jesus by the three wise men of the Bible, is an aromatic resin produced by the desert tree Commiphora myrrha. In Western Africa the hardened resin from this tree has been hand shaped into beads to be worn for decorative or other purposes.
As determined by Robert Kammerling, and described in the Fall 95 issue of Gems & Gemology (p.210), this very rare biological gem material has the following properties.
Hardness: scratched with fingernail (<2½)
Fracture: granular
Color: yellowish brown to brown
Diaphenity: translucent
Specific gravity: 1.27
Spot refractive index: 1.40
Fluorescence: LW UV (moderate, even, chalky yellow); SW UV (weak, even, chalky yellow)
Absorption spectrum (visible): cut off at 430nm
Absorption spectrum (infrared): broad peaks at 5180, 4778, 4000 cm ¯¹, sharp peaks at 4339 and 4252 cm ¯¹
Thermal stability: readily melts
Characteristic odor: sweet and spicy odor following abrasion and / or rubbing.
Myrrh, one of the three gifts to the baby Jesus by the three wise men of the Bible, is an aromatic resin produced by the desert tree Commiphora myrrha. In Western Africa the hardened resin from this tree has been hand shaped into beads to be worn for decorative or other purposes.
As determined by Robert Kammerling, and described in the Fall 95 issue of Gems & Gemology (p.210), this very rare biological gem material has the following properties.
Hardness: scratched with fingernail (<2½)
Fracture: granular
Color: yellowish brown to brown
Diaphenity: translucent
Specific gravity: 1.27
Spot refractive index: 1.40
Fluorescence: LW UV (moderate, even, chalky yellow); SW UV (weak, even, chalky yellow)
Absorption spectrum (visible): cut off at 430nm
Absorption spectrum (infrared): broad peaks at 5180, 4778, 4000 cm ¯¹, sharp peaks at 4339 and 4252 cm ¯¹
Thermal stability: readily melts
Characteristic odor: sweet and spicy odor following abrasion and / or rubbing.
Rocks, Minerals & Gemstones
By I.O.Evans
The Hamlyn Publishing Group Ltd
1972 ISBN 0-600-37537-4
The Hamlyn Publishing Group writes:
Everybody, at one time or another, has stopped in their tracks, bent down and picked up a beautifully colored or curiously shaped fragment of stone and marveled at the artistry of nature. Prehistoric man was no exception and it was not long before he realized too, the many uses to which he could put the rocks, their minerals and the gemstones. Since then man has become more and more dependent on the minerals he extracts from the Earth’s crust and today these and their derivatives make up a bewildering variety of familiar everyday objects—from out nuts and bolts and diamond rings to our computers and supersonic jet aircraft. In fact civilization as we known it is completely reliant on rocks and minerals and so their importance in our lives, and the effect that the depletion of mineral resources could have on our future, is considerable.
This book presents a broad illustrated survey of the rocks, their constituent minerals and the gemstones. The nature of the rocks, their composition and the way in which they affect the build of the countryside is discussed first (including a consideration of rocks from outer space), and then the extraction techniques of the more important mineral ores are explained, together with a summary of mineral characteristics and the various crystal systems in which minerals form. A selection of the most important and most interesting minerals then follows and details are given for each of its properties, mode of occurrence, characteristics and uses. Gemstones are discussed at length and interesting aspects range from fascinating details of diamond extraction and cutting to descriptions of gemstones of organic origin. A final very useful section deals with the practical possibilities for the rock and mineral enthusiast and includes much advice on how to collect, identify and enjoy mineral specimens.
A very readable, non-technical text is supplemented by a fine collection of over one hundred excellent photographs, thirty of which are in full color.
The Hamlyn Publishing Group Ltd
1972 ISBN 0-600-37537-4
The Hamlyn Publishing Group writes:
Everybody, at one time or another, has stopped in their tracks, bent down and picked up a beautifully colored or curiously shaped fragment of stone and marveled at the artistry of nature. Prehistoric man was no exception and it was not long before he realized too, the many uses to which he could put the rocks, their minerals and the gemstones. Since then man has become more and more dependent on the minerals he extracts from the Earth’s crust and today these and their derivatives make up a bewildering variety of familiar everyday objects—from out nuts and bolts and diamond rings to our computers and supersonic jet aircraft. In fact civilization as we known it is completely reliant on rocks and minerals and so their importance in our lives, and the effect that the depletion of mineral resources could have on our future, is considerable.
This book presents a broad illustrated survey of the rocks, their constituent minerals and the gemstones. The nature of the rocks, their composition and the way in which they affect the build of the countryside is discussed first (including a consideration of rocks from outer space), and then the extraction techniques of the more important mineral ores are explained, together with a summary of mineral characteristics and the various crystal systems in which minerals form. A selection of the most important and most interesting minerals then follows and details are given for each of its properties, mode of occurrence, characteristics and uses. Gemstones are discussed at length and interesting aspects range from fascinating details of diamond extraction and cutting to descriptions of gemstones of organic origin. A final very useful section deals with the practical possibilities for the rock and mineral enthusiast and includes much advice on how to collect, identify and enjoy mineral specimens.
A very readable, non-technical text is supplemented by a fine collection of over one hundred excellent photographs, thirty of which are in full color.
Friday, March 16, 2007
An Alternative African Source Of Vegetable Ivory
(Wahroongai News, Volume 30, No.7, July 1996) Grahame Brown writes:
Vegetable ivory, a long used effective imitation for elephant ivory, is derived from the dried nuts of several species of palm tree. The common commercial source of vegetable ivory is the Corozo or Tagua palm (Phytelephas macrocarpa) from Central America and northern South America. This ivory colored vegetable material (nut) has a hardness of 2½, a specific gravity of 1.40 – 1.43, a spot refractive index of 1.54, and in hand specimen displays the polygonal outlines of its component plant cells.
Another source of African vegetable ivory was suggested by Webster to be the Doum or Gingerbread palm (Hyphaene thebaica) of north and central Africa. According to the 5th edition of Webster’s Gems, the rounded nuts of this palm have a reddish brown skin, and edible underlying spongy layer which is commonly converted into an alcoholic beverage, and a hard inner seed (the source of vegetable ivory).
A recent purchased guide, The Shell Field Guide to the Common Trees of the Okavango Delta and the Moremi Game Reserve, by Veronica Roodt, has provided some additional details about the African source of vegetable ivory.
According to Dr Roodt, the source of vegetable ivory in the Okavango Delta—a wildlife and vegetation-rich area of 18000 km² that is the terminus of the Cubango River in Botswana—is the Real Fan Palm (Hyphanae petersania). This majestic tree grows to a height of 20m, and has a bare stem crowned by arched fan-shaped green leaves.
The tennis ball sized fruits of this palm take 2 years to mature, and up to 2 years to fall. Consequently, this palm is decorated with fruit throughout the year. The nuts of the Real Fan Palm yield a whitish milk, that resembles and tastes like coconut milk, once the hard exocarp of the nut has been fractured. The external pulp of the nut is edible, and tastes like gingerbread. It may be fermented into a very potent palm wine. The hard, hollow internal endosperm of the nut is the source of vegetable ivory.
Elephants play a major role in the dispersion of the seeds of this palm, for elephants love the taste of these nuts. The endosperm (vegetable ivory) passes through the elephant’s digestive tract unscathed and may be collected from the animal’s faeces (as large brownish furry tennis balls). If the nuts are not harvested, the faeces act as a natural fertilizer to hasten the germination of seeds.
So, there you have it; an African source of vegetable ivory confirmed, and correctly assigned to source.
Vegetable ivory, a long used effective imitation for elephant ivory, is derived from the dried nuts of several species of palm tree. The common commercial source of vegetable ivory is the Corozo or Tagua palm (Phytelephas macrocarpa) from Central America and northern South America. This ivory colored vegetable material (nut) has a hardness of 2½, a specific gravity of 1.40 – 1.43, a spot refractive index of 1.54, and in hand specimen displays the polygonal outlines of its component plant cells.
Another source of African vegetable ivory was suggested by Webster to be the Doum or Gingerbread palm (Hyphaene thebaica) of north and central Africa. According to the 5th edition of Webster’s Gems, the rounded nuts of this palm have a reddish brown skin, and edible underlying spongy layer which is commonly converted into an alcoholic beverage, and a hard inner seed (the source of vegetable ivory).
A recent purchased guide, The Shell Field Guide to the Common Trees of the Okavango Delta and the Moremi Game Reserve, by Veronica Roodt, has provided some additional details about the African source of vegetable ivory.
According to Dr Roodt, the source of vegetable ivory in the Okavango Delta—a wildlife and vegetation-rich area of 18000 km² that is the terminus of the Cubango River in Botswana—is the Real Fan Palm (Hyphanae petersania). This majestic tree grows to a height of 20m, and has a bare stem crowned by arched fan-shaped green leaves.
The tennis ball sized fruits of this palm take 2 years to mature, and up to 2 years to fall. Consequently, this palm is decorated with fruit throughout the year. The nuts of the Real Fan Palm yield a whitish milk, that resembles and tastes like coconut milk, once the hard exocarp of the nut has been fractured. The external pulp of the nut is edible, and tastes like gingerbread. It may be fermented into a very potent palm wine. The hard, hollow internal endosperm of the nut is the source of vegetable ivory.
Elephants play a major role in the dispersion of the seeds of this palm, for elephants love the taste of these nuts. The endosperm (vegetable ivory) passes through the elephant’s digestive tract unscathed and may be collected from the animal’s faeces (as large brownish furry tennis balls). If the nuts are not harvested, the faeces act as a natural fertilizer to hasten the germination of seeds.
So, there you have it; an African source of vegetable ivory confirmed, and correctly assigned to source.
The Thomas Crown Affair
Memorable quote (s) from the movie:
The Psychiatrist (Faye Dunaway): I want you to talk about women. Mr. Crown?
Thomas Crown (Pierce Brosnan): I'm sorry?
The Psychiatrist (Faye Dunaway) : Women. You get to talk about women.
Thomas Crown (Pierce Brosnan): Oh, I enjoy women.
The Psychiatrist (Faye Dunaway): Enjoyment isn't intimacy.
Thomas Crown (Pierce Brosnan): And intimacy isn't necessarily enjoyment.
The Psychiatrist (Faye Dunaway): How would you know? Has it occurred to you that you have a problem with trust?
Thomas Crown (Pierce Brosnan): I trust myself implicitly.
The Psychiatrist (Faye Dunaway): But can other people trust you?
Thomas Crown (Pierce Brosnan): Oh, you mean society at large?
The Psychiatrist (Faye Dunaway): I mean women, Mr.Crown.
Thomas Crown (Pierce Brosnan) : Yes, a woman could trust me.
The Psychiatrist (Faye Dunaway): Good. Under what extraordinary circumstances would you allow that to happen?
Thomas Crown (Pierce Brosnan): A woman could trust me as long as her interests didn't run too contrary to my own.
The Psychiatrist (Faye Dunaway): And society? If its interests should run counter to your own?
The Psychiatrist (Faye Dunaway): I want you to talk about women. Mr. Crown?
Thomas Crown (Pierce Brosnan): I'm sorry?
The Psychiatrist (Faye Dunaway) : Women. You get to talk about women.
Thomas Crown (Pierce Brosnan): Oh, I enjoy women.
The Psychiatrist (Faye Dunaway): Enjoyment isn't intimacy.
Thomas Crown (Pierce Brosnan): And intimacy isn't necessarily enjoyment.
The Psychiatrist (Faye Dunaway): How would you know? Has it occurred to you that you have a problem with trust?
Thomas Crown (Pierce Brosnan): I trust myself implicitly.
The Psychiatrist (Faye Dunaway): But can other people trust you?
Thomas Crown (Pierce Brosnan): Oh, you mean society at large?
The Psychiatrist (Faye Dunaway): I mean women, Mr.Crown.
Thomas Crown (Pierce Brosnan) : Yes, a woman could trust me.
The Psychiatrist (Faye Dunaway): Good. Under what extraordinary circumstances would you allow that to happen?
Thomas Crown (Pierce Brosnan): A woman could trust me as long as her interests didn't run too contrary to my own.
The Psychiatrist (Faye Dunaway): And society? If its interests should run counter to your own?
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