By Philip Scalisi and David Cook
Van Nostrand Reinhold Company
1983 ISBN 0-442-28685-6
Van Nostrand Reinhold Company writes:
Although we’ve been stripping classic mineral deposits for years, many of them are not even close to depletion. What’s more, new and promising repositories of valuable minerals have been discovered only recently.
Now you’ll find stimulating facts about the classic mineral and gem localities of Asia and Australia in this first volume of a series that analyzes these areas throughout the world. Accounts by mineral experts, and a bounty of illustrations confirm this volume as an all-encompassing reference that will fast become the standard in the field.
Classic Mineral Localities of the World skillfully probes geographical sites where some of the finest examples of mineral species have been uncovered. Featured maps, crystal drawings, and photographs of gems and mineral specimens are from the famous Harvard University collection and other esteemed private collections. You’ll also see plates of fine quality representative mineral specimens and gems.
The gem and mineral localities of the U.S.S.R—the Ural Mountains and Siberia—and modern classic localities—the Nuristan District of Afghanistan, Reaphook Hill in South Australia, and Yinnietharra in Western Australia—are among the areas thoroughly evaluated. Sections of Japan, China, Burma, Sri Lanka, and Iran are also explored. Extensive descriptions of the diamond mines of India are included, in addition to one of the most complete listings of all well-known Indian diamonds.
Crystallographers, professional mineralogists, geologists, and gemologists as well as gem and mineral collectors and hobbyists should have this unique handbook for its indispensable reference material.
Wednesday, March 21, 2007
Tuesday, March 20, 2007
Diamonds, Stones To Grab Further Share In Jewellery Market
(via PTI) Economic Times writes:
Diamonds and gemstones jewellery are set to grab a greater market share from plain gold and silver ornaments with prices likely to come down after import duty cuts proposed in this year's union budget, making them more affordable for Indians.
Studded jewellery has already been taking some market share from plain gold and silver jewellery over the recent years and the proposed duty cuts are likely to further scale up their demand in the Indian market, global metal consultancy firm GFMS says in its latest report.
"With the reductions in import duties on precious stones, the domestic studded jewellery would become more affordable for consumers," GFMS metal analyst Sanjiv Arole said.
India is already the world's third largest consumer of diamond jewellery after the US and Japan and a further drop in prices could precipitate some important changes in jewellery consumption patterns in the near future, GFMS said.
The production of laboratory-manufactured diamonds is also likely to increase dramatically in the coming years, it added. While lab-manufactured diamonds appear quite identical to the natural diamonds, they cost about 70 per cent less.
India, as the largest cutting and polishing centre, is likely to become one of the key regions for processing these stones and this business would ultimately find its place in the domestic jewellery markets like Surat and elsewhere in the country.
Finance Minister P Chidambaram proposed in this year's budget to reduce import duties on cut and polished diamonds, coloured stones and corals.
While coloured stones or gems are also gaining popularity among consumers, their gains are unlikely at the expense of diamonds which are showing robust growth across most of the global markets. India is one of the fastest growing diamond markets in the world yet branded diamonds segment accounts for a meagre 12 per cent. The size of the overall diamond market in India is supposed to be over 1 billion dollar. Diamonds are gradually becoming a fashion purchase with branded segment having an edge over unbranded jewellery.
Diamonds and gemstones jewellery are set to grab a greater market share from plain gold and silver ornaments with prices likely to come down after import duty cuts proposed in this year's union budget, making them more affordable for Indians.
Studded jewellery has already been taking some market share from plain gold and silver jewellery over the recent years and the proposed duty cuts are likely to further scale up their demand in the Indian market, global metal consultancy firm GFMS says in its latest report.
"With the reductions in import duties on precious stones, the domestic studded jewellery would become more affordable for consumers," GFMS metal analyst Sanjiv Arole said.
India is already the world's third largest consumer of diamond jewellery after the US and Japan and a further drop in prices could precipitate some important changes in jewellery consumption patterns in the near future, GFMS said.
The production of laboratory-manufactured diamonds is also likely to increase dramatically in the coming years, it added. While lab-manufactured diamonds appear quite identical to the natural diamonds, they cost about 70 per cent less.
India, as the largest cutting and polishing centre, is likely to become one of the key regions for processing these stones and this business would ultimately find its place in the domestic jewellery markets like Surat and elsewhere in the country.
Finance Minister P Chidambaram proposed in this year's budget to reduce import duties on cut and polished diamonds, coloured stones and corals.
While coloured stones or gems are also gaining popularity among consumers, their gains are unlikely at the expense of diamonds which are showing robust growth across most of the global markets. India is one of the fastest growing diamond markets in the world yet branded diamonds segment accounts for a meagre 12 per cent. The size of the overall diamond market in India is supposed to be over 1 billion dollar. Diamonds are gradually becoming a fashion purchase with branded segment having an edge over unbranded jewellery.
Bonnie and Clyde
Memorable quote (s) from the movie:
Buck Barrow (Gene Hackman): Hey, you wanna hear a story 'bout this boy? He owned a dairy farm, see. And his ol' Ma, she was kinda sick, you know. And the doctor, he had called him come over, and said, uh, "Uhh listen, your Ma, she's lyin' there, she's just so sick and she's weakly, and uh, uh I want ya to try to persuade her to take a little brandy," you see. Just to pick her spirits up, ya know. And "Ma's a teetotaler," he says. "She wouldn't touch a drop." "Well, I'll tell ya whatcha do, uh," - the doc - "I'll tell ya whatcha do, you bring in a fresh quart of milk every day and you put some brandy in it, see. And see. You try that." So he did. And he doctored it all up with the brandy, fresh milk, and he gave it to his Mom. And she drank a little bit of it, you know. So next day, he brought it in again and she drank a little more, you know. And so they went on that way for the third day and just a little more, and the fourth day, she was, you know, took a little bit more - and then finally, one week later, he gave her the milk and she just drank it down. Boy, she swallowed the whole, whole, whole thing, you know. And she called him over and she said, "Son, whatever you do, don't sell that cow!"
Buck Barrow (Gene Hackman): Hey, you wanna hear a story 'bout this boy? He owned a dairy farm, see. And his ol' Ma, she was kinda sick, you know. And the doctor, he had called him come over, and said, uh, "Uhh listen, your Ma, she's lyin' there, she's just so sick and she's weakly, and uh, uh I want ya to try to persuade her to take a little brandy," you see. Just to pick her spirits up, ya know. And "Ma's a teetotaler," he says. "She wouldn't touch a drop." "Well, I'll tell ya whatcha do, uh," - the doc - "I'll tell ya whatcha do, you bring in a fresh quart of milk every day and you put some brandy in it, see. And see. You try that." So he did. And he doctored it all up with the brandy, fresh milk, and he gave it to his Mom. And she drank a little bit of it, you know. So next day, he brought it in again and she drank a little more, you know. And so they went on that way for the third day and just a little more, and the fourth day, she was, you know, took a little bit more - and then finally, one week later, he gave her the milk and she just drank it down. Boy, she swallowed the whole, whole, whole thing, you know. And she called him over and she said, "Son, whatever you do, don't sell that cow!"
A Perspective On Literacy
(via TJA 29, 62, 1979) I M Darveniza writes:
1. What is literacy?
What is literacy and why do we need a perspective on it? The term has been the subject of much debate in recent years but rarely is a definition attempted. First, literacy does not just mean reading. The Concise Oxford Dictionary defines literacy as ‘the ability to read and write’. If we add to this the ability to speak our native language concisely and fluently and to listen effectively to others speaking it, we come nearer to the broader meaning of literacy; the mastery of our native language in all its aspects, as a means of communication. The mastery of these four interrelated skills, reading, writing, speaking and listening, is a long term process and an extensive program of training at all ages is necessary.
2. How to read?
Reading a text chapter once is not enough. Most students retain less than 25% of a chapter’s contents after one reading. A better method is to spend a few minutes skimming through the chapter, noting topic headings, charts and italics and reading the summary. This will give an overview of the contents and prepare for a more thorough reading. Next, turn the topic headings into questions and read for the answers. Test by trying to recall the answers. Selectively review by re-reading these sections which are not clear. If underlining is to be done, it should be done at this stage and not during the first reading of the chapter. The final step is the brief outline of the chapter.
Reading Professional Journal
Students should have the foundations of continuing education fostered through the reading of professional journals. But professional journals are voluminous and many, and a word by word reading of the relevant seeming articles is tedious and time wasting. A suggested plan to attack for keeping abreast with current papers follows:
Suggestions For Reading Professional Journals
General
Editorials
1. Preview, title, introduction (paragraph 1). Summary (last paragraph)—quickly.
2. Read: if further interested, read first sentence of the second paragraph for topic, then skip-phrase through paragraph, if it appears worthwhile. Handle remaining paragraphs the same way.
3. Review: look away from the material, verbalize the points of concern to you. Check back if necessary.
Announcements
1. Skim: for topic, if interesting to you
2. Check: for date, place, personnel
Special Articles (Historical), Etc
1. Skim: titles, for each of possible interest.
2. Check: introduction and summary. If it’s any worth to you.
3. ….handle balance of selections as with editorials.
Reviews
1. Check: bibliographic note at beginning; if of possible interest.
2. Skim: concluding paragraphs or sentences for reviewer’s summary. If you wish to know more..
3. Read: rest of review of skim-phrasing.
‘Specific’ (Reports of studies and investigations)
General Approach
1. Evaluate titles: Decide which you wish to know more about; for each.
2. Skim introduction, illustration, summary.
3. If and to the extent necessary for you, read and review article.
Evaluating a study in detail
1. What is the problem? What actually was studied may be somewhat different than the title indicates……restate the problem in your own words, if possible,
2. What type of study is it?
a. Exploratory
b. Survey
c. Descriptive
d. Experimental
3. Developing Listening Skills
Listening is the first input skill of language. In this age of media and muzak in every public place, the adolescent is a very poor listener. He is used to bring bombarded with noise, color, and fast movement and has developed the ability to isolate himself from peripheral sounds. Many of these young people have developed bad listening habits, and can tune out whatever does not ‘grab’ them. They have to be taught listening habits. A suggestion follows.
Listening
Ten bad listening habits
Bad (how to tune out)
1. calling subject uninteresting and tuning out.
2. criticizing delivery (poor organization, etc.)
3. getting overstimulated and tuning out.
4. listening only for FACTS (utterly inefficient), WORST listeners do this and think its good.
5. outlining everything (rigid)
6. faking attention.
7. tolerating or creating distractions (can’t hear speaker, etc.).
8. avoiding difficult material.
9. letting ‘emotion words’ throw you off.
10. wasting ‘the differential between speech and though speed.’ Lecturer 100 wpm; average thinker 400 wpm; Mind wanders while speaker catches up; You are tuned ‘cut for 50 in for 10’.
Good (how to overcome)
1. Can I use it? Sift, screen, bear down on subject.
2. Dig out what’s needed. Responsibility on you, not lecturer.
3. ‘Withhold evaluation until comprehension is complete’, ie. hear him out before judging.
4. Listen for ideas and concepts. Facts then arrange themselves. Helps retention.
5. Mostly you can’t. Use flexible techniques. (list of ideas and facts a good technique)—precise, abstract, etc.
6. Concentrate (who are you kidding?)
7. Eliminate them. Be aggressive about it.
8. Try it.
9. Be aware some words throw you. Don’t be thrown. Tolerate.
10. Use the time—gap to concentrate.
Three ingredients of good concentration:
- Anticipate what he’s going to say and then compare what he said with what you thought was coming.
- Identify his evidence. (This is where facts come in)
4. Lecture Notes
Taking good lecture notes is an essential component of learning a subject. However, so often this important skill is thought to be learnt by osmosis and not be teaching. A suggested plan for lecture note taking follows.
Taking Lecture Notes
There are many reasons for taking lecture notes.
- Making yourself take notes forces you to listen carefully and test your understanding of the material.
- When you are reviewing, notes provide a gauge to what is important in the text.
- Personal notes are usually easier to remember than the text.
- The writing down of important points helps you to remember them even before you have studied the material formally.
Instructors usually give clues to what is important to take down. Some of the more common clues are:
- Material written on the blackboard
- Repetition
- Emphasis
1. Emphasis can be judged by tone of voice and gesture.
2. Emphasis can be judged by amount of time instructor spends on points and number of examples he uses.
- Work signals (eg. “There are two points of view on…. The third reason is…..In conclusion…)
- Summaries given at end of class.
- Reviews given at beginning of class.
Each student should develop his own method of taking notes, but most students find the following suggestions helpful:
- Make your notes brief.
1. Never use a sentence where you can use a phrase. Never use a phrase where you can a use a word.
2. Use abbreviations and symbols.
- Put most notes in your own words. However, the following should be noted exactly.
1. Formulas
2. Definitions
3. Specific facts
- Use outline form and/or a numbering system. Indentation helps you distinguish major from minor points.
- If you miss a statement, write key words, skip a few spaces, and get the information later.
- Don’t try to use every space on the page. Leave room for coordinating your notes with text after the lecture. (You may want to list key terms in the margin or to make a summary of the contents of the page).
- Date your notes. Perhaps number the pages.
4. Developing Competence In Writing And Speaking
Discussion is as basic to good writing as it is to good oral language activities. Speaking is one of the outputs of language, the other is writing. Through talk students can develop the easy use of technical words and the fluency of expression that supports fluent writing:
- Talk gets ideas flowing
- Talk familiarizes vocabulary
- Talk provides opportunity to set out sentence patterns of constructions
- Talk promotes organization for clarity
- Talk establishes cause—effect relationship
- Talk organizes sequence of events
Quality of expression is tied to quality of input. Just as children pattern their oral language on what they hear during oral exchanges so students will absorb from their listening and reading the pattern of technical language. Academics should draw students attention to clear well written technical language.
The conventions of writing develop as students write and are interested in others reading their product. The conventions of handwriting, spelling and punctuation help to facilitate communication with the reader. Proof-reading is an essential component of good writing. Spelling of technical jargon words has to be learned, always remembering that spelling is a visual skill not an oral one (unless to confound small children).
The look of a word and the practice of writing it is important. Reading and spelling are often confused and there is concern for the ‘good’ reader who is a ‘bad’ speller. Reading is recognition while spelling is selection, e.g., pain, to spell the sound could be ai, ae, a….e, ei or ay.
Some of the points to avoid in technical writing can be itemized as follows:
1. Ambiguity: make sure writing has one meaning only.
2. Monotony of sentences: vary the length and construction of sentences.
3. Pretentious writing: do not use exaggerated expressions when simpler words will do.
4. Cliches, colloquialism, slang: look for fresher turns of phrase.
5. Unfamiliar words: do not use words if you do not know their meaning.
6. Circumlocution: be concise and to the point.
7. Unnecessary repetition: do not repeat the same word or phrase too soon. Read each paragraph as it is finished and any repetition will be noticed immediately.
1. What is literacy?
What is literacy and why do we need a perspective on it? The term has been the subject of much debate in recent years but rarely is a definition attempted. First, literacy does not just mean reading. The Concise Oxford Dictionary defines literacy as ‘the ability to read and write’. If we add to this the ability to speak our native language concisely and fluently and to listen effectively to others speaking it, we come nearer to the broader meaning of literacy; the mastery of our native language in all its aspects, as a means of communication. The mastery of these four interrelated skills, reading, writing, speaking and listening, is a long term process and an extensive program of training at all ages is necessary.
2. How to read?
Reading a text chapter once is not enough. Most students retain less than 25% of a chapter’s contents after one reading. A better method is to spend a few minutes skimming through the chapter, noting topic headings, charts and italics and reading the summary. This will give an overview of the contents and prepare for a more thorough reading. Next, turn the topic headings into questions and read for the answers. Test by trying to recall the answers. Selectively review by re-reading these sections which are not clear. If underlining is to be done, it should be done at this stage and not during the first reading of the chapter. The final step is the brief outline of the chapter.
Reading Professional Journal
Students should have the foundations of continuing education fostered through the reading of professional journals. But professional journals are voluminous and many, and a word by word reading of the relevant seeming articles is tedious and time wasting. A suggested plan to attack for keeping abreast with current papers follows:
Suggestions For Reading Professional Journals
General
Editorials
1. Preview, title, introduction (paragraph 1). Summary (last paragraph)—quickly.
2. Read: if further interested, read first sentence of the second paragraph for topic, then skip-phrase through paragraph, if it appears worthwhile. Handle remaining paragraphs the same way.
3. Review: look away from the material, verbalize the points of concern to you. Check back if necessary.
Announcements
1. Skim: for topic, if interesting to you
2. Check: for date, place, personnel
Special Articles (Historical), Etc
1. Skim: titles, for each of possible interest.
2. Check: introduction and summary. If it’s any worth to you.
3. ….handle balance of selections as with editorials.
Reviews
1. Check: bibliographic note at beginning; if of possible interest.
2. Skim: concluding paragraphs or sentences for reviewer’s summary. If you wish to know more..
3. Read: rest of review of skim-phrasing.
‘Specific’ (Reports of studies and investigations)
General Approach
1. Evaluate titles: Decide which you wish to know more about; for each.
2. Skim introduction, illustration, summary.
3. If and to the extent necessary for you, read and review article.
Evaluating a study in detail
1. What is the problem? What actually was studied may be somewhat different than the title indicates……restate the problem in your own words, if possible,
2. What type of study is it?
a. Exploratory
b. Survey
c. Descriptive
d. Experimental
3. Developing Listening Skills
Listening is the first input skill of language. In this age of media and muzak in every public place, the adolescent is a very poor listener. He is used to bring bombarded with noise, color, and fast movement and has developed the ability to isolate himself from peripheral sounds. Many of these young people have developed bad listening habits, and can tune out whatever does not ‘grab’ them. They have to be taught listening habits. A suggestion follows.
Listening
Ten bad listening habits
Bad (how to tune out)
1. calling subject uninteresting and tuning out.
2. criticizing delivery (poor organization, etc.)
3. getting overstimulated and tuning out.
4. listening only for FACTS (utterly inefficient), WORST listeners do this and think its good.
5. outlining everything (rigid)
6. faking attention.
7. tolerating or creating distractions (can’t hear speaker, etc.).
8. avoiding difficult material.
9. letting ‘emotion words’ throw you off.
10. wasting ‘the differential between speech and though speed.’ Lecturer 100 wpm; average thinker 400 wpm; Mind wanders while speaker catches up; You are tuned ‘cut for 50 in for 10’.
Good (how to overcome)
1. Can I use it? Sift, screen, bear down on subject.
2. Dig out what’s needed. Responsibility on you, not lecturer.
3. ‘Withhold evaluation until comprehension is complete’, ie. hear him out before judging.
4. Listen for ideas and concepts. Facts then arrange themselves. Helps retention.
5. Mostly you can’t. Use flexible techniques. (list of ideas and facts a good technique)—precise, abstract, etc.
6. Concentrate (who are you kidding?)
7. Eliminate them. Be aggressive about it.
8. Try it.
9. Be aware some words throw you. Don’t be thrown. Tolerate.
10. Use the time—gap to concentrate.
Three ingredients of good concentration:
- Anticipate what he’s going to say and then compare what he said with what you thought was coming.
- Identify his evidence. (This is where facts come in)
4. Lecture Notes
Taking good lecture notes is an essential component of learning a subject. However, so often this important skill is thought to be learnt by osmosis and not be teaching. A suggested plan for lecture note taking follows.
Taking Lecture Notes
There are many reasons for taking lecture notes.
- Making yourself take notes forces you to listen carefully and test your understanding of the material.
- When you are reviewing, notes provide a gauge to what is important in the text.
- Personal notes are usually easier to remember than the text.
- The writing down of important points helps you to remember them even before you have studied the material formally.
Instructors usually give clues to what is important to take down. Some of the more common clues are:
- Material written on the blackboard
- Repetition
- Emphasis
1. Emphasis can be judged by tone of voice and gesture.
2. Emphasis can be judged by amount of time instructor spends on points and number of examples he uses.
- Work signals (eg. “There are two points of view on…. The third reason is…..In conclusion…)
- Summaries given at end of class.
- Reviews given at beginning of class.
Each student should develop his own method of taking notes, but most students find the following suggestions helpful:
- Make your notes brief.
1. Never use a sentence where you can use a phrase. Never use a phrase where you can a use a word.
2. Use abbreviations and symbols.
- Put most notes in your own words. However, the following should be noted exactly.
1. Formulas
2. Definitions
3. Specific facts
- Use outline form and/or a numbering system. Indentation helps you distinguish major from minor points.
- If you miss a statement, write key words, skip a few spaces, and get the information later.
- Don’t try to use every space on the page. Leave room for coordinating your notes with text after the lecture. (You may want to list key terms in the margin or to make a summary of the contents of the page).
- Date your notes. Perhaps number the pages.
4. Developing Competence In Writing And Speaking
Discussion is as basic to good writing as it is to good oral language activities. Speaking is one of the outputs of language, the other is writing. Through talk students can develop the easy use of technical words and the fluency of expression that supports fluent writing:
- Talk gets ideas flowing
- Talk familiarizes vocabulary
- Talk provides opportunity to set out sentence patterns of constructions
- Talk promotes organization for clarity
- Talk establishes cause—effect relationship
- Talk organizes sequence of events
Quality of expression is tied to quality of input. Just as children pattern their oral language on what they hear during oral exchanges so students will absorb from their listening and reading the pattern of technical language. Academics should draw students attention to clear well written technical language.
The conventions of writing develop as students write and are interested in others reading their product. The conventions of handwriting, spelling and punctuation help to facilitate communication with the reader. Proof-reading is an essential component of good writing. Spelling of technical jargon words has to be learned, always remembering that spelling is a visual skill not an oral one (unless to confound small children).
The look of a word and the practice of writing it is important. Reading and spelling are often confused and there is concern for the ‘good’ reader who is a ‘bad’ speller. Reading is recognition while spelling is selection, e.g., pain, to spell the sound could be ai, ae, a….e, ei or ay.
Some of the points to avoid in technical writing can be itemized as follows:
1. Ambiguity: make sure writing has one meaning only.
2. Monotony of sentences: vary the length and construction of sentences.
3. Pretentious writing: do not use exaggerated expressions when simpler words will do.
4. Cliches, colloquialism, slang: look for fresher turns of phrase.
5. Unfamiliar words: do not use words if you do not know their meaning.
6. Circumlocution: be concise and to the point.
7. Unnecessary repetition: do not repeat the same word or phrase too soon. Read each paragraph as it is finished and any repetition will be noticed immediately.
Cutting Cubic Zirconia
(via Gem Cutter, March 1982) Wahroongai News writes:
We have been asked to furnish information about cutting cubic zirconia. As is usual in the faceting field, various cutters develop their own techniques but a little research brought the following results:
The recommended proportions appear to be 1/3 crown and 2/3 pavilion with the table 55% of the width. For cutting round brilliants, one cutter suggest crown mains 35º and pavilion 41º whilst another quotes 34½º and 40¾º respectively. The critical angle is specified as 28º. Yet another experienced cutter stated that the Barion cut, originally developed for diamond cutting, is quite ‘spectacular’ in cubic zirconia.
‘Make haste slowly’ is the opinion of some facetors; it is necessary to proceed by degrees. First use 600 micron diamond on a copper lap with water; followed by 1200 micron on copper with oil; then 3000 micron on copper with oil. Don’t overdo the diamond—a little goes a long way with cubic zirconia.
A smooth lap is needed—a well worn one seems to work best. And—avoid contamination at all costs! Another opinion was that one needed to use only a medium diamond disc (260 grit) and then proceed to polish. All agreed that a fine satin finish at this stage meant less polishing and that the polishing should be done with Linde A on a tin lap, well scored, and at a moderately slow speed. The only alternatives suggested were ¼ micron diamond dust on a zinc or a ceramic lap.
Incidentally, it is interesting to note that cubic zirconia was originally produced for scientific and technological purposes and its use in the gem and jewelry trade was merely a side issue. Also, the colors in which is now produced are derived by purposely adding, usually a minute quantities, some impurity (called ‘dopant’) and that many of these additives are rare-earths.
Dopant used: Cerium; Color produced: Yellow-orange-red
Dopant used: Chromium; Color produced: Olive
Dopant used: Cobalt; Color produced: Lilac
Dopant used: Copper; Color produced: Yellow
Dopant used: Erbium; Color produced: Pink
Dopant used: Europium; Color produced: Pink
Dopant used: Holmium; Color produced: Pink
Dopant used: Iron; Color produced: Yellow
Dopant used: Manganese; Color produced: Brown-violet
Dopant used: Neodymium; Color produced: Lilac
Dopant used: Nickel; Color produced: Yellow-brown
Dopant used: Praseodymium; Color produced: Amber
Dopant used: Thulium; Color produced: Green
Dopant used: Titanium; Color produced: Yellow-brown
Dopant used: Vanadium; Color produced: Green
We have been asked to furnish information about cutting cubic zirconia. As is usual in the faceting field, various cutters develop their own techniques but a little research brought the following results:
The recommended proportions appear to be 1/3 crown and 2/3 pavilion with the table 55% of the width. For cutting round brilliants, one cutter suggest crown mains 35º and pavilion 41º whilst another quotes 34½º and 40¾º respectively. The critical angle is specified as 28º. Yet another experienced cutter stated that the Barion cut, originally developed for diamond cutting, is quite ‘spectacular’ in cubic zirconia.
‘Make haste slowly’ is the opinion of some facetors; it is necessary to proceed by degrees. First use 600 micron diamond on a copper lap with water; followed by 1200 micron on copper with oil; then 3000 micron on copper with oil. Don’t overdo the diamond—a little goes a long way with cubic zirconia.
A smooth lap is needed—a well worn one seems to work best. And—avoid contamination at all costs! Another opinion was that one needed to use only a medium diamond disc (260 grit) and then proceed to polish. All agreed that a fine satin finish at this stage meant less polishing and that the polishing should be done with Linde A on a tin lap, well scored, and at a moderately slow speed. The only alternatives suggested were ¼ micron diamond dust on a zinc or a ceramic lap.
Incidentally, it is interesting to note that cubic zirconia was originally produced for scientific and technological purposes and its use in the gem and jewelry trade was merely a side issue. Also, the colors in which is now produced are derived by purposely adding, usually a minute quantities, some impurity (called ‘dopant’) and that many of these additives are rare-earths.
Dopant used: Cerium; Color produced: Yellow-orange-red
Dopant used: Chromium; Color produced: Olive
Dopant used: Cobalt; Color produced: Lilac
Dopant used: Copper; Color produced: Yellow
Dopant used: Erbium; Color produced: Pink
Dopant used: Europium; Color produced: Pink
Dopant used: Holmium; Color produced: Pink
Dopant used: Iron; Color produced: Yellow
Dopant used: Manganese; Color produced: Brown-violet
Dopant used: Neodymium; Color produced: Lilac
Dopant used: Nickel; Color produced: Yellow-brown
Dopant used: Praseodymium; Color produced: Amber
Dopant used: Thulium; Color produced: Green
Dopant used: Titanium; Color produced: Yellow-brown
Dopant used: Vanadium; Color produced: Green
Old Chinese Snuff Bottles
By Henry C Hitt
Charles E Tuttle Company
1978 ISBN 0-8048-1220-9
Charles E Tuttle Company writes:
Among collectors of Chinese snuff bottles, the name of the late Henry C Hitt has long commanded respect, not only as that of an ardent fellow collector but also as that of the author of the first book on the subject in any language—a work that had the great value of arousing collectors everywhere, even in China. This book, which appeared in first and second editions and was followed by a supplement, has in itself become a collector’s item. Until now, however, it has been practically impossible to obtain, for it was a handmade book produced by lithographic methods, and it had little hope of ever being reprinted. The present edition remedies this lack by bringing together facsimile copies of the expanded second edition (1945) and the supplement and thereby making available to a much wider audience Mr Hitt’s invaluable contribution to the fascinating subject of snuff bottle collecting.
In this introduction to the second edition, Mr Hitt wrote: “There is an almost total lack of literature on Chinese snuff bottles. This is, as far as is known, the only book on the subject, and there have been only a few magazine articles.” To be sure, since the appearance of the book in 1945 there have been numerous other books and articles on the subject, but this by no means diminishes the value of his pioneering work or the honor he achieved by being one of the first to share his knowledge with other enthusiastic collectors. And it is exactly for the benefit of these enthusiastic collectors that this new facsimile edition is being offered.
Charles E Tuttle Company
1978 ISBN 0-8048-1220-9
Charles E Tuttle Company writes:
Among collectors of Chinese snuff bottles, the name of the late Henry C Hitt has long commanded respect, not only as that of an ardent fellow collector but also as that of the author of the first book on the subject in any language—a work that had the great value of arousing collectors everywhere, even in China. This book, which appeared in first and second editions and was followed by a supplement, has in itself become a collector’s item. Until now, however, it has been practically impossible to obtain, for it was a handmade book produced by lithographic methods, and it had little hope of ever being reprinted. The present edition remedies this lack by bringing together facsimile copies of the expanded second edition (1945) and the supplement and thereby making available to a much wider audience Mr Hitt’s invaluable contribution to the fascinating subject of snuff bottle collecting.
In this introduction to the second edition, Mr Hitt wrote: “There is an almost total lack of literature on Chinese snuff bottles. This is, as far as is known, the only book on the subject, and there have been only a few magazine articles.” To be sure, since the appearance of the book in 1945 there have been numerous other books and articles on the subject, but this by no means diminishes the value of his pioneering work or the honor he achieved by being one of the first to share his knowledge with other enthusiastic collectors. And it is exactly for the benefit of these enthusiastic collectors that this new facsimile edition is being offered.
Monday, March 19, 2007
Weakly Radioactive Spinel Triplets
(via ICA Early Warning Flash, No.23, November 1989) Kurt Nassau writes:
A New York gemstone merchant accidentally placed a parcel of spinel triplets near his Geiger counter and was surprised when radioactivity was detected. Some of the stones involved were examined by me. They are yellow green, apparently intended to imitate peridot, and are said to be manufactured in Europe. Analysis shows that they consist of two layers of colorless spinel cemented together with a green lead and uranium-containing glass. The uranium provides both the color and the radioactivity. A single stone counts only just double the background on a small ‘monitor 4’ Geiger counter; accordingly the amount of radiation produced from an individual stone is not easy to detect and probably harmless. Nevertheless, significant activity is given off by a parcel containing many such stones. Gemologists and dealers should be aware of this situation.
A New York gemstone merchant accidentally placed a parcel of spinel triplets near his Geiger counter and was surprised when radioactivity was detected. Some of the stones involved were examined by me. They are yellow green, apparently intended to imitate peridot, and are said to be manufactured in Europe. Analysis shows that they consist of two layers of colorless spinel cemented together with a green lead and uranium-containing glass. The uranium provides both the color and the radioactivity. A single stone counts only just double the background on a small ‘monitor 4’ Geiger counter; accordingly the amount of radiation produced from an individual stone is not easy to detect and probably harmless. Nevertheless, significant activity is given off by a parcel containing many such stones. Gemologists and dealers should be aware of this situation.
Sideways
Memorable quote (s) from the movie:
Maya (Virginia Madsen): You know, can I ask you a personal question, Miles?
Miles Raymond (Paul Giamatti): Sure.
Maya (Virginia Madsen: Why are you so in to Pinot? I mean, it's like a thing with you.
Miles Raymond (Paul Giamatti): Uh, I don't know, I don't know. Um, it's a hard grape to grow, as you know. Right? It's uh, it's thin-skinned, temperamental, ripens early. It's, you know, it's not a survivor like Cabernet, which can just grow anywhere and uh, thrive even when it's neglected. No, Pinot needs constant care and attention. You know? And in fact it can only grow in these really specific, little, tucked away corners of the world. And, and only the most patient and nurturing of growers can do it, really. Only somebody who really takes the time to understand Pinot's potential can then coax it into its fullest expression. Then, I mean, oh its flavors, they're just the most haunting and brilliant and thrilling and subtle and... ancient on the planet.
Maya (Virginia Madsen): You know, can I ask you a personal question, Miles?
Miles Raymond (Paul Giamatti): Sure.
Maya (Virginia Madsen: Why are you so in to Pinot? I mean, it's like a thing with you.
Miles Raymond (Paul Giamatti): Uh, I don't know, I don't know. Um, it's a hard grape to grow, as you know. Right? It's uh, it's thin-skinned, temperamental, ripens early. It's, you know, it's not a survivor like Cabernet, which can just grow anywhere and uh, thrive even when it's neglected. No, Pinot needs constant care and attention. You know? And in fact it can only grow in these really specific, little, tucked away corners of the world. And, and only the most patient and nurturing of growers can do it, really. Only somebody who really takes the time to understand Pinot's potential can then coax it into its fullest expression. Then, I mean, oh its flavors, they're just the most haunting and brilliant and thrilling and subtle and... ancient on the planet.
Subscribe to:
Comments (Atom)