Sphalerite

(Blende or Zinc Blende)
Chemistry: Zinc sulphide
Crystal system: Cubic; generally in tetrahedral but also cube, octahedral, dodecahedral and trisoctahedral; twins common; massive.
Color: Transparent to translucent; yellow, green, colorless; non-gem nearly black in color.
Hardness: 3.5 - 4
Cleavage: Perfect: dodecahedral (6 directions); fracture: brittle, uneven.
Specific gravity: 4.09
Refractive index: 2.37; SR
Luster: Resinous to adamantine
Dispersion: Very high
Dichroism: -
Occurrence: Chief ore of zinc; Central Africa; Mexico; Spain.

Notes
Collector’s stone; difficult to cut due to cleavage; soft; scratches easily; has been used as prism in high R.I refractometers; may look like zircon; spectrum: 3 bands in red-690,667,651nm; faceted.

How To Separate Natural Pink Diamonds From Their Treated Counterparts

- Body color
- Color evenness
- Strain patterns
- Ultraviolet luminescence
- Spectrum

Ultraviolet luminescence + spectrum analysis are the two important tests.

Judgment Of Paris: California vs. France And The Historic 1976 Paris Tasting That Revolutionized Wine

Good Books: George M. Taber writes about the inside tale of the dramatic tasting session that transformed the wine industry. It's a trip down the memory lane. You can feel the contagious passion for his subject + he has an eye for telling detail. The book is a must-read.

This reminds me of diamond grading. Someone should do the same to transform the diamond grading tale. There is a petty war going between different diamond grading laboratories and institutes who are perceived as the gold standards of the industry. I believe it will be an interested trip down the memory lane.

Book Description:
Told for the first time by the only reporter present, this is the true story of the legendary Paris Tasting of 1976 -- a blind tasting where French judges shocked the industry by choosing unknown California wines over France's best -- and its revolutionary impact on the world of wine.

The Smithsonian's National Museum of American History houses, amid its illustrious artifacts, two bottles of wine: a 1973 Stag's Leap Wine Cellars Cabernet Sauvignon and a 1973 Chateau Montelena Chardonnay. These are the wines that won at the now-famous Paris Tasting in 1976, where a panel of top French wine experts compared some of France's most famous wines with a new generation of California wines. Little did they know the wine industry would be completely transformed as a result, sparking a golden age for viticulture that extends beyond France's hallowed borders -- to Australia, Chile, South Africa, New Zealand, and across the globe.

Then Paris correspondent for Time magazine, George M. Taber recounts this seminal contest and its far-reaching effects, focusing on the three gifted unknowns behind the winning wines: a college lecturer, a real estate lawyer, and a Yugoslavian immigrant. At a time when California was best known for cheap jug wine, these pioneers used radical new techniques alongside time-honored winemaking traditions to craft premium American wines that could stand up to France's finest.

With unique access to the main players and a contagious passion for his subject, Taber renders this historic event and its tremendous aftershocks in captivating prose, bringing to life an eclectic cast and magnificent settings. For lovers of wine and anyone who enjoys a story of the entrepreneurial spirit of the new world conquering the old, this is an illuminating and deeply satisfying tale.

Here is what Publisher's Weekly has to say about the book:
In 1976, a Paris wine shop arranged a tasting as a gimmick to introduce some California wines; the judges, of course, were all French and militantly chauvinistic. Only one journalist bothered to attend, a Time correspondent, looking for a possible American angle. The story he got turned out to be a sensation. In both red and white blind tastings, an American wine won handily: a 1973 Stag's Leap cabernet and a 1973 Chateau Montelena chardonnay. When the story was published the following week, it stunned both the complacent French and fledgling American wine industries—and things have never been the same since. Taber, the Time man, has fashioned an entertaining, informative book around this event. Following a brisk history of the French-dominated European wine trade with a more detailed look at the less familiar American effort, he focuses on the two winning wineries, both of which provide him with lively tales of colorful amateurs and immigrants making good, partly through willingness to experiment with new techniques. While the outrage of some of the judges is funny, this is a serious business book, too, sure to be required reading for American vintners and oenophiles.

Christian Vannequé, former chief sommelier at the Tour d'Argent restaurant in Paris and one of the judges at the Paris Tasting writes:
"Nearly thirty years later, Taber's book outlines an historic event that is relevant, captivating and compelling -- even for non-wine aficionados. The petty wine war that the Paris Tasting set off had one big winner: good wine. And one big loser: good wine...from France."

Industrial Strength

Peter Schjeldahl writes about Richard Serra’s work as art + its otherness @ http://www.newyorker.com/arts/critics/artworld/2007/06/11/070611craw_artworld_schjeldahl

Plonk Testing

2007: I like the the term plonk testing. Today the concept may be tricky because of the proliferation of sophisticated colored stones, treated, synthetic and assembled stones of all qualities. For the practising gemologists, gem dealers + jewelers the basic tenets are still the same: visual observation + the right approach. This requires knowledge, interpretation skills, Zen-like patience, discipline, analytical skills + hawk's eye to spot the unknown gemstone (s).

(via The Journal of Gemmology, Vol.VII, No.5, January, 1960) A F Farn writes:

My fellow gemologist and friend, Dr E H Rutland, delights in, and is an expert at ‘Plonk Testing’. To ‘plonk’ (an unusual gemological term meaning ‘to go off the deep end’) is to view a gemstone, usually not one of the better known gemstones, which has recently come to hand and to state categorically what the stone is—usually to the delight of the possessor since he is usually armed with details in advance.

A rule of thumb approach and a keen eye backed by knowledge of gemology are the essentials to expertise. Possibly the hardest school is that which backs its judgment by placing not the stone upon the refractometer but its hand in its pocket.

Having attended many lectures and listened to much theory on the subject of gem testing and the rival and relative merits of certain instruments, I am reminded of certain examination questions phrased in the following style:

- What do you consider the equipment necessary to furnish a model laboratory? or
- What are the most important or imperative instruments a gemologist’s needs?

To answer such questions one usually has or shows a marked preference for certain instruments or gives obvious indications of techniques favored by an instructor. Some people are keen on refractometer work, others specific gravity or the spectroscope, and some of course combine the use of each. There are some tests so rudimentary and positive that is needless to go further, which of course admits knowledge of gemology.

Whilst testing by sight is not necessarily accurate, it is usually applied with a background of knowledge and reasoning. I should have stated earlier that perhaps a lens is permitted, but no more. An instance of such testing could be a completely colorless (or white) stone, whichever term is preferred, with one or two minute bubbles, no double refraction discernible but perhaps a slight ‘chatter-marking’—a sure sign of heating of corundum. Therefore the stone would a synthetic corundum. This, of course, is a very obvious instance. There are, doubtless, countless others which will spring to mind. Most gemologists, of course, test stones for enjoyment at leisure; professionals test against the clock and seldom have much time to browse amongst the undoubted beauties of inclusions in Burma or Siam rubies. The latter, though less expensive commercially, are amongst the most beautiful stones from an inclusion point of view. Having tested some tens of thousands of stones I am afraid I do not linger too long in throes of delight on seeing either a Ceylon zircon spectrum or hessonite garnet inclusions. These are merely speedy recognition signs for testing.

Quite recently a parcel of 284 cts of mixed round stones of various colors, and approximately 3500 stones came into my possession. My first reaction was to glance swiftly through the stones spread out on the table on a sheet of white paper and pick out any likely stones, i.e those which looked interesting. Most seemed to me to be the product of Ceylon—later proved correct. Two stones only proved to be of a likely hue and appearance. The remainder I sorted by color into piles of brown hessonite garnets, red/pink Ceylon garnets, pale blue, green and yellow Ceylon sapphires, and an intriguing assorted colored section of zircons of every hue. The colorless portion, thank goodness, was very small—these are always a headache except in this instance.

Having decided the piles on color, the next step was to check by spectroscope. Every pink/red garnet was swiftly pushed into a spot of light from an intensity lamp focused onto the table, and the garnets fed from left to right. With the spectroscope held in the right hand some 600 stones were accurately observed and dealt with in about two hours (having all the same spectrum helped a lot). The zircons came next and the same procedure took place, except that here some had a full Ceylon spectrum and some just a hint of the 6535 Å line, some metamicts. Again this was a speedy test of approximately similar quantities and time. A point of interest here is that the quick focus spot method of scattered light will give a sharp absorption spectrum from a stone of less than one-tenth of a carat whereas by transmitted light through a microscope it would be flooded out and eye would quickly become fatigued. The next parcel, possibly the largest in number, were those ‘plonked’ as hessonites. Here there could be (I hoped) a spessartite or two and the spectroscope came into play once again. None of the stones showed a spectrum, my eye being focused on the blue section end looking for a sign of manganese in the make-up of the stone. There was no need to take the R.I of any of these stones since a quick check of samples by lens and use of corn tongs showed all had the familiar diopside crystal inclusions—the characteristic sign of hessonite. After a time, when one has concentrated solely on one color of gemstone, the eye becomes attuned and exceedingly quick to distinguish any unusual stone. These three groups had reduced the bulk by about 85%.

The next lots were the potential Ceylon sapphires. Knowledge of color shades indicated no synthetics being present, since these latter stones are usually a finer color than their natural counterparts.

Although the spectroscope was speedy in picking out green-blue sapphires, it only gave a hint of chromium being present in the pale shades of blue sapphires. This was interesting to note, since the evidence was also proved by the slight change from pale blue to pale lavender or pink when being transferred from daylight on the table to the artificial light on the focus from the intensity lamp. Although these stones were small, quite a fine bright fluorescent line could be picked up by eye on tilting the spectroscope to the left. This is a useful tip when ‘searching’ for a spectrum, e.g commercial quality Ceylon sapphires do not readily or easily show a 4500 Å line, but tilting the spectroscope will often bring it into view. (In the latter case the spectroscope is tilted to the right). Having hinted perhaps that my intuition was carried out in an atmosphere partial to absorption spectroscopy, I must state the obvious and point out that for a gemologist it is red on the left, blue on the right, when looking through a spectroscope. The pale blue and yellow sapphires together were checked by lens and tongs for chatter-marking and feathers, of which fortunately there was an abundance. Ceylon liquid feathers and two-phase inclusions are a joy in speedy establishment of origin.

The hard core of ‘seeded’ stones now came to be tested. Several mauve/brown stones proved to have the refractive index of natural spinel, two other deep golden brown stones were chrysoberyl, whilst the remainder of colorless stones, were quartz and topaz respectively. Considering its travels and origins I was lucky not to find a single paste or synthetic stone in the parcel.

Smithsonite

(Bonamite)
Chemistry: Zinc carbonate
Crystal system: Trigonal; mostly massive and stalactitic, botryoidal, granular or as encrustations; rare rhombohedral crystals are known.
Color: Translucent to opaque; light green, blue, pink, yellow, purple, rarely colorless.
Hardness: 4.5 - 5
Cleavage: Perfect: in rhombohedral; fracture: brittle, uneven.
Specific gravity: 4.3 – 4.5
Refractive index: 1.621 – 1.849; Uniaxial negative; 0.228; 1.72 mean.
Luster: Pearly-dull; rarely vitreous
Dispersion: High
Dichroism: -
Occurrence: As a secondary mineral in oxidized zone ore deposits; Greece, Mexico, USA, Spain, Namibia.

Notes
Softness makes it unsuitable for jewelry; faceted stones are collectors items; carbonate will efferverse with acid; may look like chrysoprase or turquoise; alternate name bonamite derived from name of New York jeweler who first marketed smithsonite jewelry; faceted, cabochon.

Beryl Triplets Imitating Paraiba Tourmaline

Top and bottom pieces of near colorless beryl fused together and colored by a layer of blue green glue is perceived as good imitation for Paraiba/Paraibla-like tourmaline.

The Long Tail

Good Books: (via Emergic) Chris Anderson's book, The Long Tail is about: Why the future of business is selling less of more?

From the book’s description:
The Long Tail is a powerful new force in our economy: the rise of the niche. As the cost of reaching consumers drops dramatically, our markets are shifting from a one-size-fits-all model of mass appeal to one of unlimited variety for unique tastes. From supermarket shelves to advertising agencies, the ability to offer vast choice is changing everything, and causing us to rethink where our markets lie and how to get to them. Unlimited selection is revealing truths about what consumers want and how they want to get it, from DVDs at Netflix to songs on iTunes to advertising on Google.

However, this is not just a virtue of online marketplaces; it is an example of an entirely new economic model for business, one that is just beginning to show its power. After a century of obsessing over the few products at the head of the demand curve, the new economics of distribution allow us to turn our focus to the many more products in the tail, which collectively can create a new market as big as the one we already know.

The Long Tail is really about the economics of abundance. New efficiencies in distribution, manufacturing, and marketing are essentially resetting the definition of what’s commercially viable across the board. If the 20th century was about hits, the 21st will be equally about niches.

The Economist wrote: The niche, the obscure and the specialist, Mr Anderson argues, will gain ground at the expense of the hit. As evidence, he points to a drop in the number of companies that traditionally calculate their revenue/sales ratio according to the 80/20 rule -- where the top fifth of products contribute four-fifths of revenues. Ecast, a San Francisco digital jukebox company, found that 98% of its 10,000 albums sold at least one track every three months. Expressed in the language of statistics, the experiences of Ecast and other companies such as Amazon, an online bookseller, suggest that products down in the long tail of a statistical distribution, added together, can be highly profitable. The internet helps people find their way to relatively obscure material with recommendations and reviews by other people (and for those willing to have their artistic tastes predicted by a piece of software) computer programs which analyse past selections.

The Wall Street Journal wrote in a review:
In a traditional graph of sales and demand, there is a stratospheric swoop upward where hot products and services are tracked, and a long descending line tracing the less spectacular performance of low-volume also-rans. For years, these outliers fell off the edge of the market or held only a marginal position, with minimal profits. These days, though, technology has allowed such niche interests to thrive, finding steady customers and rising levels of interest.

The long tail has lifted into prominence troupes like the Lonely Island, or bands like the Arctic Monkeys (popularized by MySpace, the user-generated site aimed at young people), or art-house movies like "Capturing the Friedmans" (made popular through Netflix, the online-based movie-rental outfit). Thanks to technology's power to target pockets of consumers, niche forms of cultural expression are reaching otherwise fractional audiences, and the fractions are adding up in ways they never have before. In the process, the economy is reshaped, and our tastes are too.

Blockbuster may have to devote its (limited) shelf space to 50 copies of the latest action blockbuster; Netflix can (theoretically) offer every movie ever made. Through sophisticated filtering, Netflix and Amazon and iTunes can make a deep inventory pay off by matching niches with consumers. Technology has shattered an aggregate popular culture -- the icon-producing kind. But it has also come to its rescue.

Steven Johnson wrote about the book: It occurred to me reading The Long Tail that the general trend from mass to niche can explain some of this increased complexity: niches can speak to each other in shorthand; they don't have to spell everything out. But at the same time, the niche itself doesn't have to become any more aesthetically or intellectually rich compared to what came before. If there's a pro wrestling niche, the creators don't have to condescend to the non-wrestling fans who might be tuning in, which means that they can make more references and in general convey more information about wrestling -- precisely because they know their audience is made up of hard core fans. But it's still pro wrestling. The content isn't anything to write home about, but the form grows more complex. In a mass society, it's harder to pull that off. But out on the tail, it comes naturally.An example from the book: What’s extraordinary is that virtually every single one of those tracks [on Rhapsody] will sell. From the perspective of a store like Wal-Mart, the music industry stops at less than 60,000 tracks. However, for online retailers like Rhapsody the market is seemingly never-ending. Not only is every one of Rhapsody’s top 60,000 tracks streamed at least once each month, but the same is true for its top 100,000, top 200,000, and top 400,000 -- even its top 600,000, top 900,000, and beyond. As fast as Rhapsody adds tracks to its library, those songs find an audience, even if it’s just a handful of people every month, somewhere in the world. This is the Long Tail?

The New Yorker wrote:
Both eBay and Google turn out, in Anderson’s account, to be long-tail businesses, too. On any given day, about thirty million individual items are bought and sold on eBay, many of them cheap and obscure. Barely a decade after Pierre Omidyar founded eBay, more than seven hundred thousand Americans report it as their primary or secondary source of income, according to a study by the market-research firm AC Nielsen. For Google, the long tail is populated by small advertisers. Major corporations pay to get their ads placed next to the results of popular search terms, such as luxury S.U.V.s and flat-screen televisions. But much of Google’s annual revenue, which now exceeds five billion dollars, comes from tiny companies whose ads appear next to queries like Victorian jewelry and Hudson Valley inns....The forces behind the long tail are largely technological: cheap computer hardware, which reduces the cost of making and storing information products; ubiquitous broadband, which cuts the cost of distribution; and elaborate filters, such as search engines, blogs, and online reviews, which help to match supply and demand. Think of each of these three forces as representing a new set of opportunities in the emerging Long Tail marketplace, Anderson suggests. The democratized tools of production are leading to a huge increase in the number of producers. Hyper-efficient digital economies are leading to new markets and marketplaces. And finally, the ability to tap the distributed intelligence of millions of consumers to match people with the stuff that suits them best is leading to the rise of all sorts of new recommendation and marketing methods, essentially serving as the new tastemakers.

The Long Tail is a must-read book. The book aggregates a variety of concepts + how technology links niche interests to thrive in a natural way + reshaping economy and tastes.

Big Ideas

Peter Schjeldahl writes about the Venice Biennale—the most venerable of international art shows—directed by the American curator, critic, and teacher Robert Storr + other viewpoints @ http://www.newyorker.com/arts/critics/artworld/2007/06/25/070625craw_artworld_schjeldahl

Rough Diamonds’ Fatigue

Chaim Even-Zohar writes about worldwide rough diamond (2005) production (s) + the London connection + the South Africa connection + Dubai / Swiss connection (s) + Australia / London / Belgium connection (s) + the rough diamonds that never made it to London + other viewpoints @ http://www.idexonline.com/portal_FullEditorial.asp?TextSearch=&KeyMatch=0&id=25508

Black Opaque Gem Materials

Hematite
RI: 2.94-3.22; SG: 4.95-5.16; Luster: Metallic; Comments: Sometimes magnetic

Uraninite
SG: 5.2-10.0; Luster: Submetallic, resinous; Comments: Radioactive

Diamond
RI: 2.417; SG: 3.52; Luster: Adamantine

Irradiated Black Diamond
RI: 2.417; SG: 3.52; Luster: Adamantine; Comments: Sometimes radioactive

Cassiterite
RI: 2.006-2.097; SG: 6.99; Luster: Adamantine to vitreous

Hausmannite
RI: >1.81; SG: 4.84; Luster: Adamantine

Psilomelane (Mn oxides)
RI: > 1.81; SG: 4.35; Luster: Metallic to submetallic

Spinel Group
Magnetite
RI: 2.42; SG: 5.20; Luster: Metallic; Comments: Magnetic
Hercynite
RI: >1.81; 1.835; SG: 4.40; Luster: Subadamantine; Comments: Sometimes magnetic
Spinel
RI: 1.77; SG: 3.83; Luster: Vitreous
Intermediate spinel-hercynite
RI: 1.765; SG: 3.93; Luster: Subadamantine to vitreous

Garnet Group
Andradite garnet (melanite)
RI: 1.885; SG: 3.84; Luster: Subadamantine to vitreous
Pyrope
RI: 1.740; SG: about 3.72; Luster: Vitreous

Corundum (star sapphire)
RI: 1.760-1.78; SG: 3.989-4.0; Luster: Subadamantine to vitreous

Pyroxene Group
Augite
RI: 1.702-1.728; SG: 3.20-3.35; Luster: High vitreous
Diopside (star)
RI: 1.675-1.701; SG: 3.33; Luster: Vitreous
Jadite jade
RI: 1.65-1.67; SG: 3.20-3.34; Luster: Vitreous
Tourmaline
RI: 1.622-1.655; SG: 3.15-3.20; Luster: Vitreous

Amphibole Group
Ferrohornblende
RI: 1.60-1.70; SG: 3.36; Luster: Vitreous
Nephrite jade
RI: 1.600-1.641; SG: 2.90-3.02; Luster: Vitreous
Cummingtonite-grunerite
RI: 1.54-1.65

Jet
RI: 1.59-1.66; SG: 1.20-1.30; Luster: Resinous

Ekanite
RI: 1.593-1.595; SG: about 3.30; Luster: Vitreous: Comments: Radioactive

Labradorite Feldspar
RI: 1.560-1.568; SG: 2.69; Luster: Vitreous; Comments: Colored by inclusions

Dyed Chalcedony (black onyx)
RI: 1.530-1.539; SG: 2.57-2.64; Luster: Vitreous

Chalcedony with Psilomelane
RI: 1.535-1.539; SG: 3.0-3.1; Luster: Metallic to submetallic; Comments: Banded

Coated Quartz
RI: 1.54; Luster: Vitreous to dull

Dolomite
RI: 1.51-1.67; SG: 2.8-2.9; Luster: Vitreous

Black Coral
RI: 1.56; SG: 1.34; Luster: Resinous

Obsidian
RI: 1.48-1.52; SG: 2.30-2.50; Luster: Vitreous

Opal (black opaque)
RI: 1.44; SG: 2.02; Luster: Vitreous

Rocks (aggregates)
Dolomite/quartzite rock
RI: 1.66 spot; SG: 2.74; Luster: Vitreous

Simulants
Cubic zirconia
RI: 2.14; SG: 6.14-6.16; Luster: Adamantine
Silicon
RI: >1.81; SG: 2.34; Luster: Metallic: Comments Gray
Hematine
RI: >1.81; SG: 4.00-7.00; Luster: Metallic; Comments: Magnetic
YIG (ytrrium iron garnet)
SG: about 6; Luster: Vitreous to submetallic; Comments: Magnetic
Barrium sulfate/polymer
RI: mid-1.50s; SG: 2.26-2.33
Plastics
RI: 1.5-1.6; SG: 1.05-1.55; Luster: Vitreous to resinous
Glass
RI: 1.35-1.70; SG: 2.51-3.21; Luster: Submetallic to vitreous

Smaragdite

(variety of Actinolite)
Crystal system: Monoclinic; massive.
Color: Translucent to opaque: yellowish green to bluish green.
Hardness: 6.5
Cleavage: -
Specific gravity: 3.25
Refractive index: 1.608 – 1.630; Biaxial negative; 0.022; 1.62 mean.
Luster: Vitreous
Dispersion: -
Dichroism: -
Occurrence: Austria, France, Italy, USA, Philippines

Notes
Chloromelanite may be a variety; part of the amphibole group of minerals; difficult to distinguish from jadeite to which it is closely related; carvings.

Buying Gold? Getting Cheated!

Ronojoy Banerjee writes about the survey (I wasn't surprised) conducted by The Bureau of Indian Standards on the purity of gold in India @ http://www.outlookmoney.com/scripts/ptifile.asp?pti_news_id=738

More Than You Know

Good Books: (via Emergic) Michael Mauboussin is chief investment strategist at Legg Mason Capital. His book More Than You Know is a collection of his essays written over the past few years.

Here is what Publisher’s Weekly has to say (via Amazon.com):
Mauboussin is not your average Wall Street equity analyst, writing investment recommendations whose topical interest wanes a few days after the report is issued. His strategy reports begin with scientific findings from diverse fields, then show why an investor should care. This book is a collection of 30 short reports, revised and updated, covering animal behavior ("Guppy Love: The Role of Imitation in Markets"), psychology ("Why Zebras Don't Get Ulcers"), philosophy of science ("The Janitor's Dream: Why Listening to Individuals Can be Hazardous to Your Wealth") and other fields. Each essay describes a fascinating scientific finding, then develops and applies it to personal investing. "Survival of the Fittest," for example, begins by discussing how Tiger Woods improved his golf swing, introduces the concept of fitness landscapes from evolutionary biology, then explains why investors in commodity-producing companies should like strong centralized management, while technology-stock buyers should prefer flexible organizations with lots of disruptive new ideas. The book is breezy and well written, but not dumbed down, and provides extensive references. It can be read for entertainment as popular science or to broaden your investment thinking.

You can find some of Mauboussin’s recent essays here.

This is a fascinating book + gem and jewelry professionals + entrepreneurs must read the book for insights because you will meet the same type of characters in the (any) industry.

Modern Love

Peter Schjeldahl writes about the art and style of Sara & Gerald Murphy@ http://www.newyorker.com/arts/critics/artworld/2007/08/06/070806craw_artworld_schjeldahl

Canadian Diamond Anti-Money Laundering Rules In-The-Making

Chaim Even-Zohar writes about Canadian government's overstated concerns posed by the diamond industry + BHP Billiton's suggestions on the methodology of reporting transactions + client identification difficulties + AML/CFT compliance agenda (s) + other viewpoints @ http://www.idexonline.com/portal_FullEditorial.asp?TextSearch=&KeyMatch=0&id=25527

Thermal Conductivity

With the rapid advancements in the field of crystal growth in the past several years, materials produced for the purpose of simulating diamond have become more and more difficult to detect. Because the R.I’s (refractive index) of diamond and most simulants are over the limit of the conventional refracatometer, identification is more difficult.

In 1978, the Ceres Corporation, which is a large manufacturer of synthetic cubic zirconia, came out with completely new type of instrument for the separation of diamond from the various simulants. The instrument is termed a ‘thermal conductivity probe’ and operates on the principle of thermal (heat) conductivity. Diamond is unique in this property and even the most impure Type I stones still conduct heat many times quicker than the next best material.

Since the Ceres probe was developed many other companies have also developed similar instruments. They usually consist of a small box with a meter or lights to indicate whether or not the stone is diamond. A pen-like probe is attached to the box by a wire. The conductivity of the stone is tested by pressing the copper tip of the probe against the stone. An electrical current is passed through a thermister in contact with the stone which heats it up slightly. Then the current is cut off and sensors measure the speed with which it cools. Diamond, having the highest thermal conductivity, cools tip faster than any other material.

The advantages of the thermal conductivity probe are many. Any size stone from 0.03 carat up can be tested, mounted or unmounted. The quality of the polish or thin surface coatings does not affect the accuracy.

Advantages
- Stones down to 0.03 carat can be tested.
- Mounted or unmounted stones can be tested.
- Faceted or rough stones can be tested.
- Doublets can be tested if several parts of the stone are checked.
- Thin surface coatings on the stone do not affect the accuracy.
- Each stone takes only about 3 seconds to test.
- The test is extremely accurate, especially for materials which closely resemble diamond in appearance.

Disadvantages
- The probe only indicates whether or not a stone is diamond. It does not distinguish between various simulants.
- As with any instrument, there is chance for error if it is not used properly or if it was manufactured poorly.

The thermal conductivity probes offer the gemologist an accurate and quick means of distinguishing between diamond and its simulants. If used properly by a trained gemologist, the results are both accurate and repeatable.

Scheelite

Chemistry: Calcium tungstate.
Crystal system: Tetragonal; dipyramids (may look like octahedral) or tabular crystals, also granular masses.
Color: Transparent to translucent; colorless, brown, orange, yellow, purple.
Hardness: 4.5 - 5
Cleavage: Perfect: 1 direction: fracture: splintery, sub-conchoidal to uneven.
Specific gravity: 5.9 – 6.1
Refractive index: 1.918 – 1.934; Uniaxial positive; 0.016
Luster: Vitreous to adamantine.
Dispersion: Medium
Dichroism: Strong.
Occurrence: Metamorphic, hydrothermal and pegmatites; Mexico, USA, Italy, UK.

Notes
May be dyed to look like many other stones; fine yellow may look like fancy diamond, but DR; also made synthetically; fluorescence: strong blue in short wave, but no reaction in long wave; may show didymium spectral lines in yellow and green; faceted for collectors.

Other People's Money

Memorable quotes from the movie:

Lawrence Garfield (Danny DeVito): This company is dead. I didn't kill it. Don't blame me. It was dead when I got here. It's too late for prayers. For even if the prayers were answered, and a miracle occurred, and the yen did this and the dollar did that and the infrastructure did the other thing, we would still be dead. You know why? Fiber optics. New technologies. Obsolescence. We're dead, all right. We're just not broke. And do you know the surest way to go broke? Keep getting an increasing share of a shrinking market. Down the tubes, slow but sure.

How To Grade Tea

Grading tea is an art than science + it owes its special effect to its caffeine, tannins, amino acid, protein content (s) + trace element (s): fluoride, potassium, calcium, manganese, vitamins: niacin, vitamin B1 and B2 + it acts directly on the brain and central nervous system (s) + it increases concentration.

Look how similar the concept is to diamond grading (old + new terms) + colored stone grading: it's either the color (due color causing trace elements), saturation or tone (based on percentage of elements + other modifiers) + other factors (like clarity + size, shape, proportion, symmetry, finish) that creates a unique gradation.

- Whole Leaf

- Flowery Orange Pekoe (FOP)

- Golden Flowery Orange Pekoe (GFOP)
- FOP with golden tips

- Tippy Golden Flowery Orange Pekoe (TGFOP)
- FOP with lots of golden tips

- Finest Tippy Golden Flowery Orange Pekoe (FTGFOP)
- Exceptional quality FOP

- Special Finest Tippy Golden Flowery Orange Pekoe (SFTGFOP)
- The very best FOP

- Orange Pekoe (OP)

- Pekoe (P)

- Flowery Pekoe (FP)

- Pekoe Souchong (PS)

- Souchong (S)

Experts may also add 1 to decribe top quality after leaf designation (s): like FTGFOP1, OP1, S1 and so on.

- Broken Leaf
- Broken Orange Pekoe (BOP), Golden Broken Orange Pekoe (GBOP), Flowery Broken Orange Pekoe (FBOP), Tippy Golden Broken Orange Pekoe (TGBOP), Golden Flowery Broken Orange Pekoe (GFBOP), Tippy Golden Flowery Broken Orange Pekoe (TGFBOP)

- Fannings
- Broken Orange Pekoe Fannings (BOPF)

- Dust
- Broken Orange Pekoe Dust (BPOD), Pekoe Dust (PD), Red Dust (RD), Super Red Dust (SRD), Fine Dust (FD), Super Fine Dust (SFD), Golden Dust (GD)

The grades of tea are represented by initials or a series of initials. Here are the grades of leaf sizes from largest to smallest:

- Whole Leaf
- Souchon
- FOP: Flowery Orange Pekoe
- OP: Orange Pekoe

- Broken Leaf
- P: Pekoe
- BOP: Broken Orange Pekoe

- Fannings and Dust
- F: Fannings
- D: Dust

- Additional Modifiers
- T: Tippy
- G: Golden

Usually they start at the lowest grade PS (Pekoe Souchong) to FOP (higher quality). They may also add modifiers such as GFOP (Golden Flowery Orange Pekoe) + even more modifiers such FTGFOP (Finest Tippy Golden Flowery Orange Pekoe) + SFTGFOP (Special Finest Tippy Golden Flowery Orange Pekoe) to improve the overall quality.