How To Separate Frequently Encountered Blue Stones

- Visual observation: (10x lens) Look for color, luster, cut, doublet/triplet junctions, if any.

- Determine optic character: Single refractive (SR) / Double refractive (DR) / Anomalous Double
refractive (ADR) / Aggregate (AGG).

- Spectrum: Many blue stones may have diagnostic spectrum.

- Microscope: Inclusions may be diagnostic, but look for inclusions that differentiate natural and
synthetic, doublet / triplet.

- Dichroscope: Different cutting orientations of natural and synthetic corundum may be revealed by dichroscope.

- Fluorescence: Look under shortwave and longwave for diagnostic colors.

- Immersion cell: Use immersion cell and high refractive index liquid to separate doublets/triplets.

- Refractometer: Confirm spectroscope reading with refractometer.

The blue stones, which may resemble one another in appearance and values, are:

Synthetic blue quartz

- Hardness: 7
- Specific gravity: 2.65
- Refractive index: 1.54 – 1.55
- Optic sign: Uniaxial positive
- Birefringence: DR; 0.009
- Other points: Color, inclusions, interference figures, if seen, spectrum. Common look-alikes include aquamarine, blue spinel, blue sapphire, blue topaz, and glass. Standard / analytical techniques may be required to identify the stones.

Iolite

- Hardness: 7.5
- Specific gravity: 2.60
- Refractive index: 1.54 – 1.55
- Optic sign: Biaxial negative
- Birefringence: DR; 0.009
- Other points: Color, pleochroism, inclusions. Iolite may be treated. Common look-alikes include amethyst, tanzanite, blue sapphire, blue spinel, blue tourmaline, tanzanite and glass. Standard / analytical techniques may be required to identify the stones.

Beryl (aquamarine)

- Hardness: 7.75
- Specific gravity: 2.70-2.90
- Refractive index: 1.56 – 1.59
- Optic sign: Uniaxial negative
- Birefringence: DR; 0.005/9
- Other points: Color, inclusions. Aquamarine may be treated. Common look-alikes include blue topaz and glass. Standard / analytical techniques may be required to identify the stones.

Beryl (maxixe-type)

- Hardness: 8
- Specific gravity: 2.70 – 2.90
- Refractive index: 1.56 – 1.59
- Optic sign: Uniaxial negative
- Birefringence: DR; 0.005/9
- Other points: Color (unstable color; fades), inclusions. Maxixe type beryl may be treated, and may look like aquamarine, tanzanite, synthetic blue quartz, and glass. Standard / analytical techniques may be required to detect treatments / identify the stones.

Blue topaz

- Hardness: 8
- Specific gravity: 3.56
- Refractive index: 1.61 – 1.62
- Optic sign: Biaxial positive
- Birefringence: DR; 0.010
- Other points: Color. Blue topaz may be treated. Most gem quality stones are relatively clean. Blue topaz may look like aquamarine, blue sapphire, blue spinel, iolite, synthetic blue quartz and glass. Standard / analytical techniques may be required to detect treatments / identify the stones.

Apatite
- Hardness: 5
- Specific gravity: 3.18
- Refractive index: 1.63 – 1.64
- Optic sign: Uniaxial negative
- Birefringence: DR; 0.002- 4 (average)
- Other points: Color, spectrum, dichroism, inclusions. Gem quality stones may be relatively clean. Apatite may look like blue spinel, blue sapphire, blue topaz, blue tourmaline, and glass. Standard / analytical techniques may be required to identify the stones.

Tourmaline
- Hardness: 7
- Specific gravity: 3.05
- Refractive index: 1.62 – 1.64
- Optic sign: Uniaxial negative
- Birefringence: DR; 0.018
- Other points: Color, inclusions, pleochroism, doubling of back facets. Tourmaline may be treated. Gem quality stones are relatively clean. Common look-alikes include blue sapphire, blue spinel, apatite, blue topaz, tanzanite, iolite and glass. Standard / analytical techniques may be required to detect treatments / identify the stones.

Tanzanite (Zoisite)

- Hardness: 6.5
- Specific gravity: 3.35
- Refractive index: 1.69 – 1.70
- Optic sign: Biaxial positive
- Birefringence: DR; 0.009
- Other points: Color, pleochroism, inclusions. Tanzanites may be treated. Gem quality stones relatively clean. Common look-alikes include blue sapphire, iolite, tourmaline, amethyst and glass. Standard / analytical techniques may be required to detect treatments / identify the stones.

Spinel

- Hardness: 8
- Specific gravity: 3.60+
- Refractive index: 1.718
- Optic sign: SR
- Birefringence: -
- Other points: Color, spectrum, inclusions. Gem quality blue spinels may be clean. Common look-alikes include blue sapphire, blue tourmaline, iolite, tanzanite, amethyst and glass. Standard / analytical techniques may be required to identify the stones.

Synthetic blue spinel

- Hardness: 8
- Specific gravity: 3.63
- Refractive index: 1.728
- Optic sign: SR
- Birefringence: -
- Other points: Color, inclusions, Chelsea color filter, fluorescence. Standard identification techniques may be required to identify the stones.

Sapphire

- Hardness: 9
- Specific gravity: 4
- Refractive index: 1.76 – 1.77
- Optic sign: Uniaxial negative
- Birefringence: DR; 0.008
- Other points: Color, inclusions, fluorescence, spectrum. Use microscope to separate natural from synthetic. Sapphires may be treated. Gem quality stones are relatively clean. Common look- alikes include tanzanite, blue spinel, blue topaz, blue tourmaline, synthetic blue quartz, iolite and glass. Standard / analytical techniques may be required to detect treatments / identify the stones.

Synthetic sapphire

- Hardness: 9
- Specific gravity: 4
- Refractive index: 1.76 – 1.77
- Optic sign: Uniaxial negative
- Birefringence: DR; 0.008
- Other points: Color, inclusions, fluorescence, spectrum. Use microscope to separate flame fusion from flux from hydrothermal stones. Gem quality stones are relatively clean. Analytical techniques may be required to identify the stones.

Benitoite

- Hardness: 6.5
- Specific gravity: 3.67
- Refractive index: 1.76 – 1.80
- Optic sign: Uniaxial positive
- Birefringence: DR; 0.047
- Other points: Color, inclusions, fluorescence, spectrum, dispersion. Standard / analytical techniques may be required to identify the stones.

Blue zircon

- Hardness: 7.5
- Specific gravity: 4.69
- Refractive index: 1.93 – 1.99
- Optic sign: Uniaxial positive
- Birefringence: DR; 0.059
- Other points: Color, inclusions, spectrum, doubling of back facets, negative refractive index reading, luster, abraded facet junctions. Common look-alikes include blue sapphire, blue topaz, aquamarine, synthetic blue quartz and glass. Gem quality stones are relatively clean. Standard / analytical techniques may be required to detect treatments / identify the stones.

Blue diamond

- Hardness: 10
- Specific gravity: 3.52
- Refractive index: 2.42
- Optic sign: SR/ADR
- Birefringence: -
- Other points: Rare; Color, inclusions, fluorescence, spectrum. Blue diamonds may be treated. Gem quality stones are relatively clean. Analytical techniques may be required to detect treatments.

Synthetic blue diamond

- Hardness: 10
- Specific gravity: 3.52
- Refractive index: 2.42
- Optic sign: SR/ADR
- Birefringence: -
- Other points: Color, inclusions, fluorescence, spectrum. Synthetic blue diamonds are produced by high pressure high temperature method. Gem quality stones are relatively clean. Analytical techniques may be required to identify the stones.

Synthetic blue cubic zirconia

- Hardness: 8.5
- Specific gravity: 5.65 +
- Refractive index: 2.15 +
- Optic sign: SR
- Birefringence: -
- Other points: Color, negative refractive index reading, luster, dispersion. Standard / analytical techniques may be required to identify the stones.

Glass

- Hardness: 5.5
- Specific gravity: 3.70
- Refractive index: 1.60 – 1.66
- Optic sign: SR
- Birefringence: -
- Other points: Color, soft, inclusions (gas bubbles, swirls), luster, Chelsea color filter (for cobalt rich stones), spectrum. Standard / analytical techniques may be required to identify the stones.

Assembled Stones

Doublets / Triplets

Corundum composites (natural crown/synthetic base)
Refractive index: 1.76 – 1.77
Birefringence: DR; 0.008
Other points: Immersion (Look for differences in color and luster between the sections)

Synthetic spinel soude (spinel / spinel)
- Refractive index: 1.728
- Optic sign: SR/ADR
- Birefringence: -
- Other points: Look for differences in color and luster between the sections, gas bubbles)

Garnet topped doublet (glass)
- Refractive index: 1.76 +
- Optic sign: SR/ADR
- Birefringence: -
- Other points: Look for differences in color and luster between the sections, gas bubbles)

Gemstones

By Eduard Gubelin and Franz-Xaver Erni
2000 GeoScience Press Inc, Tucson, Arizona
ISBN 0-945005-36-9

GeoScience Press Inc writes:

This book offers the reader a deep insight into the fascinating world of gemstones. It provides an exact description of the individual gems and goes into their origins and their extraction. In this graphic style, Eduard Gubelin reports on the events deep inside the Earth aeons ago that led to the creation of these superlative, sparkling natural products and their colorful radiance. Even if these wonders of Nature can be reduced to chemical formulae, they nevertheless lose nothing of the fascination that they have had for humans since time immemorial.

Franz-Xaver Erni offers the reader a spellbinding tale of how gemstones have loyally accompanied humans throughout history. How gemstones have served women as jewelry and men as symbols of their power. The loveliest of gems adorn women’s jewelry as well as the crowns and insignia of worldly and spiritual rulers.

Throughout ages, individual gems have been allocated to the months of the year and to the signs of the zodiac and imbued with special healing powers in popular imagination. This book offers qualified answers to all questions relating to gemstones; it is not only an exciting read but also a reference work that can be consulted as required.

About the authors

Dr. Eduard J Gubelin is one of the foremost gemologists in the world.

Dr Franz-Xaver Erni is a freelance journalist (PEN).

The Great Book Of Jewels

By Ernst A and Jean Heiniger
Edita S.A, Lausanne, Switzerland
1974
ISBN 0-517-18132-0

Edita S.A writes:

Through all of the recorded history, jewels have exerted a powerful influence on affairs of men. The Great Book Of Jewels is the first book to capture all the history, romance, intrigue, and enduring beauty of precious stones, from their earliest history to present. The editors, Ernst and Jean Heiniger, aided by a team of nine distinguished gemologists from the world’s foremost museums have amassed a wealth of jewelry lore and scientific fact which they illustrate with man’s most dazzling gems, all newly photographed especially for this book.

Obtaining permission to take these photographs and plotting the historical provenance of the gems required a double genius for diplomacy and persistence. It was also the source of a rich yield of anecdotes, retold in the introduction. Almost five years in the preparation, this work is the result of painstaking research, infinite patience, and thousands of miles of air and automobile travel to three continents. The gemstones you see in this book lie closely guarded in museums, private collections, and darkened bank vaults all over the world. Many have never been available for public inspection.

Synthetic Star Stones

In 1947, the Linde Company began producing synthetic star corundum by the Verneuil (flame fusion) process. Star boules were made by adding 0.1-0.3% of titanium oxide to the mixture. After the boules have cooled, they are reheated to a temperature of 1100-1500ºC for a period of several hours to several days. This causes the titanium oxide to be exsolved in the form of needles arranged in intersecting sets, just like the natural star corundum. The stones, which are known as Linde Stars in the trade are currently produced in several colors, with red and blue being the most common.

For many years they were produced in the United States and often had engraved “L” on the base of the cabochon, which stood for Linde. Today the stones are produced in several other countries as well.

Identification of synthetic star corundum is not a problem because the needles are more evenly distributed and stars appear too good. For now synthetic star is produced by the flame fusion process, and the stones show curved growth lines and gas bubbles characteristic of this process.

How To Separate Frequently Encountered Fancy Colored Diamonds From Imitations

- Visual observation: (10x lens) Look for color, luster, cut, doublet/triplet junctions, if any.

- Determine optic character: Single refractive (SR) / Double refractive (DR) / Anomalous Double refractive (ADR) / Aggregate (AGG).

- Spectrum: Many stones may have diagnostic spectrum.

- Microscope: Inclusions may be diagnostic, but look for inclusions that differentiate natural and synthetic, doublet / triplet.

- Fluorescence: Look under shortwave and longwave for diagnostic colors.

- Immersion cell: Use immersion cell and high refractive index liquid to separate doublets/triplets.

- Refractometer: Confirm spectroscope reading with refractometer.

The fancy colored stones, which may resemble one another in appearance and values, are:

Diamond

- Hardness: 10
- Specific gravity: 3.52
- Refractive index: 2.42
- Optic sign: SR/ADR
- Birefringence: -
- Other points: negative refractive index, dispersion, luster, look at the girdle plane; cleavage, inclusions, weak to strong fluorescence in long wave (may be inert). Diamonds may be treated. Sapphire, synthetic sapphire, spinel, synthetic spinel, zircon, synthetic rutile, synthetic yttrium aluminum garnet (YAG), synthetic gadolium gallium garnet (GGG), synthetic strontium titanate, synthetic cubic zircona (CZ), topaz, quartz, demantoid garnet, sphene, and glass may look like diamond. Standard / analytical techniques may be required to detect treatments / identify the stones.

Synthetic cubic zirconia

- Hardness: 8.5
- Specific gravity: 5.60 – 6.0
- Refractive index: 2.15 – 2.18 (average)
- Optic sign: SR
- Birefringence: -
- Other points: color, negative refractive index, dispersion, luster, orange flash on the pavilion, girdle, inclusions, fluorescence. Gem quality stones are relatively clean. Standard / analytical techniques may be required to identify the stones.

Synthetic strontium titanate

- Hardness: 5.5
- Specific gravity: 5.13
- Refractive index: 2.41
- Optic sign: SR
- Birefringence: -
- Other points: color, negative refractive index, dispersion, luster, girdle, inclusions, fluorescence, rounded facet edges. Gem quality stones are relatively clean. Standard / analytical techniques may be required to identify the stones.

Synthetic gadolium gallium garnet (GGG)

- Hardness: 6.5
- Specific gravity: 7.05
- Refractive index: 1.97
- Optic sign: SR
- Birefringence: -
- Other points: color, negative refractive index, dispersion, luster, girdle, color, inclusions, fluorescence (strong orange yellow (LW) and yellow (SW)), rounded facet edges. Gem quality stones are relatively clean. Standard / analytical techniques may be required to identify the stones.

Synthetic yttrium aluminum garnet (YAG)

- Hardness: 8.5
- Specific gravity: 4.58
- Refractive index: 1.83
- Optic sign: SR
- Birefringence: -
- Other points: color, negative refractive index, dispersion, luster, girdle, inclusions, fluorescence (variable). Gem quality stones are relatively clean. Standard / analytical techniques may be required to identify the stones.

Synthetic rutile

- Hardness: 6.5
- Specific gravity: 4.25
- Refractive index: 2.61 – 2.90
- Optic sign: Uniaxial positive
- Birefringence: DR; 0.287
- Other points: color, negative refractive index, strong dispersion, luster, doubling of back facets, inclusions, rounded facet edges. Gem quality stones are relatively clean. Standard / analytical techniques may be required to identify the stones.

Demantoid garnet

- Hardness: 6.5
- Specific gravity: 3.85
- Refractive index: 1.89
- Optic sign: SR
- Birefringence: -
- Other points: color, negative refractive index reading, dispersion. Gem quality stones are relatively clean. Standard / analytical techniques may be required to identify the stones.

Zircon

- Hardness: 7.5
- Specific gravity: 4.69
- Refractive index: 1.93 -1.99
- Optic sign: Uniaxial positive
- Birefringence: DR; 0.059
- Other points: color, dispersion, negative refractive index, luster, inclusions, doubling of back facets, spectrum. Gem quality stones are relatively clean. Standard / analytical techniques may be required to identify the stones.

Sphene

- Hardness: 5.5
- Specific gravity: 3.53
- Refractive index: 1.89 – 2.02
- Optic sign: Biaxial positive
- Birefringence: DR; 0.13
- Other points: color, dispersion, negative refractive index, luster, inclusions, doubling of back facets, spectrum. Gem quality stones are relatively clean. Standard / analytical techniques may be required to identify the stones.

Benitoite

- Hardness: 6.5
- Specific gravity: 3.67
- Refractive index: 1.76 – 1.80
- Optic sign: Uniaxial positive
- Birefringence: DR; 0.047
- Other points: Color, inclusions, fluorescence, spectrum, dispersion. Standard / analytical techniques may be required to identify the stones.

Diamond-studded future for Botswana

(via National Jeweler Network) iAfrica writes:

Botswana, the world's largest diamond producer, is targeting a 17-fold increase in its fledgling cutting industry within five years.

It also aims to provide its diamond mines with all support services from local sources, President Festus Mogae said on Tuesday. He announced that the local cutters would be part supplied direct from a producer, as well as the De Beers' Diamond Trading Company, which until now has been the exclusive marketing channel for Botswana production.

Diamond centre
"We can and will graduate from a diamond producing country to a world class diamond centre," Mogae told delegates from the international industry at a dinner in Antwerp, Belgium.

"The cutting and polishing industry in Botswana has been very small, cutting diamonds worth about $30-million per annum. It is our wish the 16 companies now licensed to operate in Botswana should in five years' time be cutting and polishing at least half a billion dollars worth of diamonds per annum," he said.

Botswana was aiming to develop its diamond industry, not only to polish and cut stones across the market, but also to provide all other financial and technical support services. This would be helped by the migration to Botswana by 2008 of industry services carried out by the De Beers' Diamond Trading Company (DTC) in London, primarily the aggregation of rough production.

"This will attract related services to Botswana, such as diamond banking, security, insurance, security, technology and engineering as well as grading or diamond laboratories," Mogae said.

Better balance
He has previously stated that a major reason for development of cutting and polishing was to help alleviate Botswana's growing unemployment; but in Antwerp stressed this must not happen by the industry concentrating on lesser skilled operations to satisfy the larger volumes sold at the lower end of the market.

"We hope that there will be a balance between employment creation through the cutting of smaller goods and profitable operation which means cutting higher value goods. It is indeed our hope that all companies will do everything possible to ensure employment creation but we also recognise that they should be viable," he said.

The DTC's Botswana operation (DTCB) would become operational in 2008 and be a joint partnership between De Beers and the Botswana government, as is its present diamond producer Debswana.

"All diamond manufacturers in Botswana will become clients of DTCB," Mogae said. "It will supply them with mixtures rather than Debswana-only production, at DTC determined prices which we trust will be market related."

Allay fears
Whilst Debswana markets exclusively through the DTC, the local cutters would also be supplied direct by Diamonex, an Australian- and Botswana-listed company whose projects are entirely in Botswana. Its Martin's Drift property, due to commence production during 2007, comprises kimberlites previously discovered by De Beers.

"The diamonds from this producer will be made available to companies in Botswana outside of the DTC system, also at market prices. They will only be exported if the cutting and polishing companies in Botswana do not buy them," Mogae said.

This is not seen as the beginning of a move towards direct marketing of all Botswana production but rather as a possible way to allay fears that bringing rough diamonds onto the market in Botswana might open up a channel for the introduction of conflict diamonds.

De Beers and Botswana were architects of the Kimberley Process, which seeks to prevent trade in the small number of gems produced to fund conflict in Africa. Last year, De Beers Botswana chief executive, Sheila Khama, registered concern about opening the sealed and secure process to sell to local cutters.

"Nothing we do to develop the cutting and polishing industry will be allowed to interfere with the Kimberley Process," she said.

More info @ http://business.iafrica.com/news/590862.htm

The Diamond World

By David E Koskoff
Published by Harper & Row Publishers, New York
ISBN 0-06-038005-5
1981

Harper & Row Publishers writes:

When Randolph Churchill, father of Winston, peered down into the vastness of “The Big Hole of Kimberley”, the great worked out diamond mine, and contemplated what it represented in human terms, he mused. “All for the vanity of woman.” To which one of the women in the party added, “And the depravity of man.” The Diamond World is about the vanity of women and the depravity of men.

On one level, of course, the book is about diamonds: it traces the stone from mine to finger. On another level, though, this book is about very different matters: smuggling in Zaire (DR Congo), corruption in Sierre Leone, income tax evasion in Israel, child labor in India, murder in New York and perversion of Japanese values. An incisive economic dissection of the world’s most glittering business, this book is also an anthropological, sociological, and political look at the world’s shabbiest business—the diamond trade.

The Diamond World is about the ways in which De Beers Consolidated Mines Limited, the giant South African corporation that controls diamond distribution, has attained and maintained control of the diamond world, and the benevolent and malevolent faces of its power. It is about the diamantaires; the people involved in one or more aspects of the diamond industry and trade, and about the honor code that governs them, and which makes them quite possibly the world’s most honest businessmen—within their own group. Their honor code, however, has never had much relevance to the outside world; they victimize both consumers and the countries that shelter them, particularly the United States, Israel, and Belgium.

The diamond world is so secretive that even its New York labor union has an unlisted telephone number. “It’s like a prison system,” one customs official told the author. “If you talk,’ others won’t deal with you, buy from you or sell to you.” Nonetheless, with gall and charm—and mostly perseverance—David Koskoff worked his way into the arcane and colorful circle of the diamond people and managed to interview hundreds of them: small ‘diamond diggers’ prospecting for diamonds with more hope than knowledge; De Beers and other diamond mining executives on three continents; twelve-year old diamond polishers in the diamond cottages of India; jewelers in high priced goods and in schlock. Mostly people were evasive; with few exceptions; they do have something to hide. But from fragments of each person’s comments, Koskoff was able to piece together the puzzle of the diamond world. In the process he traveled around the world—to Amsterdam and Antwerp, Tel Aviv, India, Hong Kong, Tokyo; to South Africa, Namibia, Botswana, Zaire, Ghana, Liberia and Sierre Leone.

There have been other books about the diamond world, but none that has so totally bared the inner machinations of the world’s most mysterious business.

About The Author

David E Koskoff, a practicing attorney, is the author of Joseph P Kennedy; A Life and Times and The Mellons: The Chronicle of America’s Richest Family. He lives in Plainville, Connecticut, with his wife, Charlotte.

David E Koskoff writes:

“Get the coat! Get the coat!” Harry Samuelson’s father yelled from the ship’s railing to his son on the wharf. “Go back to the hotel, pay the bill, and get the coat!”

Harry suspected what was afoot. The ship, from Virgo, Spain, to Cuba, was fully booked; the Samuelsons had appreciated that they would have to wait for the next boat to freedom. They had done to the docks only to say goodbye to some luckier friends, other Jewish refugees from Hitler, who had obtained the last berths available. Once aboard, though, the friends warned Harry’s father: Spain might change its tolerant policy toward the Jews; there might not be a next boat. This might be the Samuelson’s last chance to escape. The friends were willing to help. At length Harry’s father made the determination: They would stow away. Standing on the wharf, Harry, fifteen years old, pieced that much together.

But why the coat? What of their luggage, their important belongings? Why had his father neglected to mention these things of value? In Cuba it would be warm; his father would not even need an overcoat.

Harry rushed back to the hotel, threw the family’s most valuable possessions into a suitcase, and with a mine-is-not-to-reason-why sigh, put the useless overcoat on his own back and returned to the dock. With a surreptitiously obtained pass, he boarded ship, and when it embarked for Cuba and freedom, the Samuelsons—seven in all—were aboard, secreted in their friend’s cabin.

When the ship was well at sea, the Samuelsons confided in a Catholic priest, who brought young Harry to see the ship’s purser to make the family’s explanations and try to smooth things over. The purser was outraged to learn that there were stowaways on his ship and was not to be mollified by a mere boy. He demanded to see Harry’s father immediately.

Harry was terrified. Would they order that the ship be turned around, and hand the family over to the authorities as common criminals? Or worse, deport them to Spain across the border to Vichy France, where the Nazis were in firm control? He returned to the family’s hiding place where his father calmly heard what had occurred.

No, the father would not go to see the purser. Instead, he said, Harry must return to see the purser—this time alone, without the priest. He was to tell the purser that they were honest people, that they would pay for the passage, that they were grateful for his understanding and for his assistance, and—fumbling about in the lining of his old overcoat—that they wanted the purser to have a token of their appreciation. The father removed his hand from within the coat and dropped something into Harry’s palm: one shiny pebble.

Today Harry Samuelson is an important diamond dealer in Antwerp, Belgium, the capital of the world diamond trade. He has forgotten much in a full life, but he will always remember the look on the purser’s face when Harry gave him the diamond. “You can’t imagine how his face lit up; I saw a smile like I’ve never seen in my whole life.” And he remembers the wonderful trip to Cuba—everything was first class al the way. He remembers, too, the coat, the old overcoat, and what was sewn into his lining, the family’s passport to freedom.

How To Separate Frequently Encountered Green Stones

- Visual observation: (10x lens) Look for color, luster, cut, doublet/triplet junctions, if any.

- Determine optic character: Single refractive (SR) / Double refractive (DR) / Anomalous Double refractive (ADR) / Aggregate (AGG).

- Spectrum: Many green stones may have diagnostic spectrum.

- Microscope: Inclusions may be diagnostic, but look for inclusions that differentiate natural and synthetic, doublet / triplet.

- Dichroscope: Different cutting orientations of natural and synthetic corundum / beryl may be revealed by dichroscope.

- Fluorescence: Look under shortwave and longwave for diagnostic colors.

- Immersion cell: Use immersion cell and high refractive index liquid to separate doublets/triplets.

- Refractometer: Confirm spectroscope reading with refractometer.

The green stones, which may resemble one another in appearance and values, are:

Fluorite

- Hardness: 4
- Specific gravity: 3.18
- Refractive index: 1.434
- Optic sign: SR
- Birefringence: -
- Other points: Inclusions, color, Chelsea color filter. Fluorite may be treated. Gem quality fluorites are relatively clean. Common look-alikes include emerald, tsavorite garent, peridot, demantoid garnet, green sapphire and glass. Standard / analytical techniques may be required to detect treatments / identify the stones.

Chalcedony (stained)

- Hardness: 6.5
- Specific gravity: 2.60
- Refractive index: 1.53 (mean)
- Optic sign: AGG (aggregate)
- Birefringence: -
- Other points: Color, stain, Chelsea color filter, inclusions. Chalcedony may be treated. Common look-alikes include jadeite jade, nephrite jade and glass. Standard identification techniques may be required to detect treatments.

Emerald

- Hardness: 7.5
- Specific gravity: 2.70 (average)
- Refractive index: 1.57 – 1.58
- Optic sign: Uniaxial negative
- Birefringence: DR; 0.006
- Other points: Color, inclusions, spectrum, fluorescence. To separate natural vs synthetic use microscope. Most emeralds are treated. Clean emeralds are difficult to find. Common look-alikes include fluorite, tsavorite garnet, demantoid garnet, peridot and glass. Standard / analytical techniques may be required to detect treatments / identify the stones.

Synthetic emerald

- Hardness: 7.5
- Specific gravity: 2.70 (average)
- Refractive index: 1.57 – 1.58
- Optic sign: Uniaxial negative
- Birefringence: DR; 0.003
- Other points: Color, inclusions, fluorescence, spectrum. Flux and hydrothermal stones may show diagnostic inclusions. Most gem quality stones are relatively clean. Standard / analytical techniques may be required to identify the stones if they are clean.

Tourmaline

- Hardness: 7
- Specific gravity: 3.05
- Refractive index: 1.62 – 1.64
- Optic sign: Uniaxial negative
- Birefringence: DR; 0.018
- Other points: Color, pleochroism, inclusions. Most tourmalines are treated. Gem quality stones are relatively clean. Common look-alikes include peridot, tsavorite garnet, chrome diopside, green sapphire, emerald and glass. Standard / analytical techniques may be required to detect treatments / identify the stones.

Jadeite jade

- Hardness: 7
- Specific gravity: 3.34
- Refractive index: 1.66 (mean)
- Optic sign: AGG (aggregate)
- Birefringence: -
- Other points: Color, inclusions, spectrum, Chelsea color filter. Most jadeite jades are treated. Common look-alikes include nephrite jade, chalcedony, serpentine, green zoisite, soapstone, idocrase, aventurine quartz and glass. Standard / analytical techniques may be required to detect treatments.

Peridot

- Hardness: 6.5
- Specific gravity: 3.34
- Refractive index: 1.65 – 1.69
- Optic sign: Biaxial positive
- Birefringence: DR; 0.037
- Other points: Color, inclusions, spectrum, birefringence, doubling of back facets. Common look-alikes include tourmaline, chrome diopside, tsavorite garnet, demantoid garnet, green sapphire and glass. Standard identification techniques may be required to identify the stones.

Enstatite

- Hardness: 5.5
- Specific gravity: 3.20 – 3.00
- Refractive index: 1.65 – 1.68
- Optic sign: Biaxial positive
- Birefringence: DR; 0.010
- Other points: Color, inclusions, spectrum. Enstatite may look like peridot. Standard identification techniques may be required to identify the stones.

Diopside

- Hardness: 5
- Specific gravity: 3.30
- Refractive index: 1.67 – 1.70
- Optic sign: Biaxial positive
- Birefringence: DR; 0.025
- Other points: Color, inclusions, doubling of back facets. Common look-alikes include tourmaline, tsavorite garnet, demantoid garnet, peridot, green sapphire and glass. Gem quality stones are relatively clean. Standard identification techniques may be required to identify the stones.

Green zoisite

- Hardness: 6.5
- Specific gravity: 3.35
- Refractive index: 1.69 – 1.70
- Optic sign: Biaxial positive
- Birefringence: DR; 0.009
- Other points: Color, pleochroism, inclusions. Green zoisite may be treated. Gem quality stones are relatively clean and may look like alexandrite. Translucent to opaque quality stones may look like jadeite jade, aventurine quartz or glass. Standard / analytical techniques may be required to detect treatments / identify the stones.

Tsavorite garnet

- Hardness: 7.25
- Specific gravity: 3.65
- Refractive index: 1.75
- Optic sign: SR
- Birefringence: -
- Other points: Color, inclusions. Common look-alikes include chrome diopside, green tourmaline, green sapphire, demantoid garnet, peridot, emerald and glass. The stones may be treated. Gem quality stones are relatively clean. Standard / analytical techniques may be required to identify the stones.

Demantoid garnet

- Hardness: 6.5
- Specific gravity: 3.85
- Refractive index: 1.89
- Optic sign: SR
- Birefringence: -
- Other points: Color, inclusions, spectrum, dispersion, negative refractive index. Common look-alikes include tsavorite garnet, green tourmaline, chrome diopside, green sapphire, peridot, emerald and glass. The stones may be treated. Standard / analytical techniques may be required to detect treatments / identify the stones.

Chrysoberyl

- Hardness: 8.5
- Specific gravity: 3.72
- Refractive index: 1.74 – 1.75
- Optic sign: Biaxial positive
- Birefringence: DR; 0.009
- Other points: Color, inclusions, spectrum. Common look-alikes include green sapphire, tsavorite garnet, demantoid garnet, peridot, tourmaline, fluorite and glass. The stones may be treated. Standard / analytical techniques may be required to detect treatments / identify the stones.

Green sapphire

- Hardness: 9
- Specific gravity: 4
- Refractive index: 1.76 – 1.77
- Optic sign: Uniaxial negative
- Birefringence: DR; 0.008
- Other points: Color, inclusions, spectrum. Common look-alikes include tsavorite garnet, demantoid garnet, green zircon, peridot, chrome diopside, green tourmaline and glass. The stones may be treated. Standard / analytical techniques may be required to identify treatments / identify the stones.

Green zircon

- Hardness: 6.5
- Specific gravity: 4
- Refractive index: 1.82 (values are variable)
- Optic sign: Uniaxial positive
- Birefringence: DR; 0.01
- Other points: Color, inclusions, negative refractive index, doubling of back facets, spectrum. Common look-a likes include green sapphire, peridot, chrome diopside, peridot, chrysoberyl, tsavorite garnet, demantoid garnet, emerald and glass. The stones may be treated. Standard / analytical techniques may be required to detect treatments / identify the stones.

Synthetic cubic zirconia

- Hardness: 8.5
- Specific gravity: 5.65 +
- Refractive index: 2.15 +
- Optic sign: SR
- Birefringence: -
- Other points: Color, negative refractive index reading, luster, dispersion. Standard / analytical techniques may be required to identify the stones.

Diamond

- Hardness: 10
- Specific gravity: 3.52
- Refractive index: 2.42
- Optic sign: SR/ADR
- Birefringence: -
- Other points: Rare; color, negative refractive index reading, luster, dispersion, spectrum, inclusions. Green diamonds may be treated. Analytical techniques may be required to detect treatments.

Syntheic green diamond

- Hardness: 10
- Specific gravity: 3.52
- Refractive index: 2.42
- Optic sign: SR/ADR
- Birefringence: -
- Other points: Color, negative refractive index reading, luster, dispersion, spectrum, inclusions. Synthetic diamonds are produced by high pressure high temperature method. Gem quality stones are relatively clean. Analytical techniques may be required to identify the stones.

Glass

- Hardness: 5.5
- Specific gravity: 3.70
- Refractive index: 1.60 – 1.66
- Optic sign: SR
- Birefringence: -
- Other points: Color, soft, inclusions (gas bubbles, swirls), luster. Standard identification techniques may be required to identify the stones.

Assembled Stones

Doublets / Triplets

Beryl composites
Refractive index: 1.57 -1.59
Birefringence: DR; 0.004
Other points: Immersion (Look for differences in color and luster between the sections)

Quartz soude (quartz/quartz)
- Refractive index: 1.54 -1.59
- Optic sign: Uniaxial positive
- Birefringence: DR; 0.009
- Other points: Look for differences in color and luster between the sections, gas bubbles)

Synthetic spinel soude (spinel / spinel)
- Refractive index: 1.728
- Optic sign: SR/ADR
- Birefringence: -
- Other points: Look for differences in color and luster between the sections, gas bubbles)

Garnet topped doublet (glass)
- Refractive index: 1.76 +
- Optic sign: SR/ADR
- Birefringence: -
- Other points: Look for differences in color and luster between the sections, gas bubbles)