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Search Results for: gemstone library

Gemstone Library

The following gemstones are the more popular ones usually found in retail-stores. The text was compiled from the highly recommended “Jewelry & Gems – The Buying Guide” by Antoinette L. Matlins & A.C. Bonnano.

AMETHYST

amethA transparent purple variety of quartz,is one of the most popular of colour gems. The birthstone of February, it was once believed to prevent the wearer from getting drunk, and if the circle of the sun or moon was engraved thereon, it was believed to prevent death from poison. Available in shades from light to dark purple, it is relatively hard, fairly brilliant, and overall a good, versatile, wearable stone, available in good supply even in very large sizes (although large sizes with deep colour are now becoming scarce). Amethyst is probably one of the most beautiful stones available at a moderate price, although one must be careful because “fine” amethyst is being produced synthetically today. It frequently exhibits colour zoning (often looking like chevrons). Amethyst may fade from heat and strong sunshine.

AQUAMARINE

aquaA universal symbol of youth, hope, and health, blesses those born in March. (Prior to the fifteenth century it was thought to be the birth stone for those born in October.) Aquamarine is a member of the important beryl family, which includes emerald, but aquamarine is less brittle and more durable than emerald. Aquamarine ranges in colour from light blue to bluish green to deep blue, which is the most valuable and desirable colour. It is a very wearable gem, clear and brilliant, and, unlike emerald, is available with excellent clarity even in very large sizes, although these are becoming scarce today. One must be careful not to mistake blue topaz for aquamarine. While topaz is an equally beautiful gem, it is usually much less ex pensive since it is usually treated to obtain its desirable colour. For those who can’t afford an aquamarine, however, blue topaz is an excellent alternative – as long as it is properly represented … and priced. Also, note that many aquamarine-colored synthetic spinels are erroneously sold as aquamarine.

CITRINE

citrOften called quartz topaz, citrine topaz, or topaz, all of which are misleading. It is yellow, amber, to amber brown. While a pleasing stone in terms of colour, and fairly durable, citrine is slightly softer and has less brilliance than precious topaz. It also lacks the subtle colour shading, the pinkier yellow or pinkish amber shades, which lend to precious topaz a distinctive colour difference. (Much citrine is made by heat-treating purple amethyst.) Citrine is also much less expensive than precious topaz. It should never be represented as topaz, which technically is “precious” or “imperial” topaz. Citrine is plentiful in all sizes, and can be made into striking jewellery, especially in very large sizes, for a relatively small investment.

EMERALD

emerThe green variety of the mineral beryl and one of the most highly prized of all the gems. Aside from being the birthstone for May, it was historically believed to bestow on its wearer faithful ness and unchanging love, and was thought to enable the wearer to forecast events. The finest-quality emerald has the colour of fresh young green grass an almost pure spectral green, possibly with a very faint tint of blue, as in the “drop of oil” emerald from Colombia, which is considered to be the world’s finest. Although a hard stone, emerald will chip easily since it tends to be somewhat brittle, so special care should be given in wearing and handling. Because of emerald’s popularity and value, imitations are abundant. Glass (manufactured complete with “flaws”), doublets or triplets such as “aquamarine emeralds” and “Tecla emeralds,” which are clever imitations made by inserting layers of green glass (or, more frequently, a green cementing agent) between pieces of aquamarine or quartz “crystal” are often encountered. Also, fine synthetic emeralds have been produced for many years with nearly the same physical and optical properties (colour, hardness, brilliance) as genuine emerald. Techniques to enhance colour and reduce the visibility of flaws are also frequently used. A common practice is to boil the emerald in oil (sometimes tinted green), a practice that goes back to early Greek times. This is a widely accepted trade practice, since it is actually good for the stone in light of its fragile nature. Oiling hides some of the whitish flaws, which are actually cracks, filling the cracks so they be come less visible. The oil becomes an integral part of the emerald un less it is subjected to some type of degreasing procedure. The development and use of the ultrasonic cleaner has brought to light the extensiveness of this practice. Never clean emeralds in an ultrasonic cleaner.

GARNET

garnet Belongs to one of the most exciting families in the gem world. A hard, durable, often very brilliant stone, available in many colours (greens, reds, yellows, oranges), it offers far greater versatility and opportunity for the jewellery trade than has yet been capitalised upon. Depending upon the variety, quality, and size, lovely garnets are available for under $20 per carat or more than $3,000 per carat. Garnet also occurs in certain shades of red that have been taken for some varieties of ruby. And in yellow it has been confused with precious topaz. Garnet can be found in almost every colour and shade except blue. It is best known in a deep red variety, sometimes with a brownish cast, but it is commonly found in orangish brown shades, and brilliant wine red shades as well. Other colours include orange, red purple, violet, and pink.

OPAL

opal Whose brilliance and vibrant colours resemble the colours of the fall, is certainly appropriate as a birthstone for October. When we try to describe the opal, we realise how insufficient the English language is. It is unique among the gems, displaying an array of very brilliant miniature rainbow effects, all mixed up together. Its most outstanding characteristic is this unusual, intense display of many colours flashing out like mini-rainbows. This effect is created by opal’s formation process, which is very different from that of other gems. Opal is composed of hydrated silica spheres. The mini rainbows seen in most opals result from light interference created by these spheres. The arrangement of the spheres, which vary in size and pattern, is responsible for the different colours seen. Opal is usually cut flat or in cabochon, since there is no additional brilliance to be captured by a good faceting job. Colour is everything. The more brilliant the colour, the more valuable the gem. It is probably truer of opal than any other stone that the more beautiful the stone and its colour, the more it will cost.

PERIDOT

peridotThe birthstone for August. Peridot was also a favourite of the ancients. This lovely transparent yellowish green to deep chartreuse stone was quite a powerful gem. It was considered an aid to friendship and was also believed to free the mind of envious thoughts. (Which is probably why it was an aid to friendship.) Because of its yellowish green colour, it was also believed to cure or prevent diseases of the liver and dropsy. And, if that’s not enough, if worn on the left arm it would protect the wearer from the evil eye. It is also popular today, but probably more for its depth of green colour than its professed powers. While not particularly brilliant, the richness of its colour is exceptional. It comes in shades of yellowish green to darker, purer green colours. It is available in small sizes; larger sizes are becoming scarce. It is not a hard stone and may scratch easily. Also, some stones may look like peridot (green sapphire, green troumaline) and be mistaken for peridot and be misrepresented.

RUBY

ruby Birthstone for July. Ruby is the red variety of the mineral corundum. Historically, it has been symbolic of love and passion, considered to be an aid to firm friendship, and believed to ensure beauty. Its colour ranges from purplish or bluish red to a yellowish red. The finest colour is a vivid, almost pure spectral red with a very faint undertone of blue, as seen in Burmese rubies, which are considered the finest. The ruby is a very brilliant stone and is also a very hard, durable, and wearable stone (a hardness of 9 on Mohs’ scale). Because of these characteristics, ruby makes an unusually fine choice for any piece of jewellery. As it is true for other popular gems – the greater the value and demand, the greater the use of techniques to “improve” or to simulate. Again, examples of almost every type of technique can be found: colour enhancement, synthesis, substitutes, doublets, triplets, misleading names, etc. The newest synthetic rubies – the Kashan ruby and Chatham ruby – are so close to natural ruby in every aspect that many are actually passing for genuine. When getting a very fine, valuable ruby certified, make every effort to select a gemmologist with both many years’ experience in coloured gems and an astute knowledge of the marketplace today.

SAPPHIRE

sapphBirthstone of September. The finest sapphires are considered to be the blue variety – specifically those from Burma and Kashmir, which are closest to the pure spectral blue. Fine, brilliant, deep blue Burmese sapphires will surely dazzle the eye and the pocketbook, as will the Kashmir, which is a fine velvety-toned deep blue. Many today tend to be too dark, how ever, because of the presence of too much black and poor cutting (cutting deep for additional weight), but the deep blues can be treated to lighten the colour. The Ceylon sapphires are a very pleasing shade of blue, but are a less deep shade than the Burmese or Kashmir, often on the pastel side. We are also seeing many Australian sapphires. These are often a dark blue, but have a slightly green undertone, as do those from Thailand, and sell for much less per carat. They offer a very afford able alternative to the Burmese, Kashmir, or Ceylon, and can still be very pleasing in their colour. Blue sapphires also come from Tanzania, Brazil, Africa, and even the U.S.A. (Montana and North Carolina). They also come in other colours, especially yellow and pink, and in smaller sizes some beautiful shades of green. These are known as fancy sapphires. Compared to the cost of blue sapphire and ruby, these stones offer excellent value and real beauty. Techniques have been developed to treat natural sapphires to remove a certain type of flaw (needle type) and to change the colour for example, to create a “Ceylon” sapphire that never came from Ceylon (Sri Lanka) but whose colour looks like that of a Ceylon.

TANZANITE

tanzA variety of the mineral zoisite was not considered a gem material until 1967, when a beautiful, rich, blue to purple blue, transparent variety was found in Tanzania (hence tanzanite). Tanzanite can possess a rich, sapphire blue colour (possibly with some violet red or greenish yellow flashes). This lovely gem can cost over $2,000 per carat today in larger sizes. But one must be cautious. It is relatively soft, so we do not recommend tanzanite for rings (unless it’s set in a very protected setting) or for everyday wear in which it would be exposed to knocks and other abuse. One must also be aware that a very inexpensive, dull, brownish zoisite can become a beautiful, expensive tanzanite after heat treatment.

TOPAZ

topaz A symbol of love and affection is the birthstone for November. It is one of nature’s most wonderful and least-known families. The true topaz is rarely seen in jewellery stores. Unfortunately, most people know only the quartz (citrine) topaz, or glass. In the past almost any yellow stone was called topaz. True topaz is very beautiful and versatile. Topaz occurs not only in the transparent yellow, yellow brown, orangy brown, and pinky brown colours most popularly associated with it, but also in a very light to medium red (now found naturally in fair supply, although many are produced through heat treatment), very light to light blue (also often the result of treatment, although it does occur naturally on a fairly wide scale), very light green, light greenish yellow, violet, and colourless. Topaz is a hard, brilliant stone with a fine colour range, but it is much rarer and much more expensive than the stones commonly sold as topaz. There are many misleading names to suggest that a stone is topaz when it is not, for example, “Rio topaz,” “Madeira topaz,” “Spanish topaz,” and “Palmeira topaz.” They are types of citrine (quartz) and should be represented as such. Blue topaz has become very popular in recent years; most of it treated (there is no way yet to determine which have been treated and which are natural). It closely resembles the finest aquamarine (which is very expensive today) and offers a very attractive, and much more affordable alternative.

TOURMALINE

turm A gem of modern times, but nonetheless has found its way to the list of birthstones, becoming an “alternate birthstone” for October. Perhaps this honor results from tourmaline’s versatility and broad color range. Or perhaps to the fact that red-and-green tourmaline, in which the red and green occur side by side in the same stone, is reminiscent of the turning of October leaves. Whatever the case, tourmaline is one of the most versatile of the gem families. It is available in every color, in every tone, from deep to pastel and even with two or more colors appearing in the same stone, side by side. There are bicolored tourmalines (half red and the other half green, for example) and tricolored (one-third blue, one-third green, and one-third yet another color). The fascinating “watermelon” tourmaline looks just like the inside of a watermelon-red in the center surrounded by a green “rind.” Tourmaline is a fairly hard,durable, brilliant, and very wearable stone with a wide choice of colours.

TSAVORITE

tsavo A member of the garnet family and is often mistaken for other (usually more expensive) gems. It is one of the most beautiful, and all but a few would assume it was an emerald of the finest quality. In fact, it is “clearer,” more brilliant, and more durable. There is also a rarer green garnet, called demantoid, which costs slightly more than tsavorite but which, although slightly softer, has more fire. These gems offer fine alternatives to the person desiring a lovely green gem who can’t afford emerald. While still rare, expensive gems themselves, they are far less expensive than an emerald of comparable quality.

 

Visit also the following pages in GEMOLOGY WORLD:

  • MEXICAN OPAL SAFARI – A visit to an opal mine in Querétaro, Mexico.
  • GEM MINING IN SRI LANKA – An exciting trip to the gem mines of Elahera, Sri Lanka.
  • GEMSTONE PRODUCTION IN THAILAND – A visit to Chantaburi, Thailand.
  • SOUTH SEA PEARL PRODUCTION – A visit to a South Sea Pearl Farm.
  • VISIT TO IDAR-OBERSTEIN – Europe’s gem centre.
  • THE SAPPHIRE MINES IN PAILIN, CAMBODIA.
  • EMERALDS OF BRAZIL – Mining in the Nova Era.
  • EMERALDS OF MUZO – A visit to the famous emerald mines in Colombia.
  • AUSTRALIA GEMSAFARI 2006 – visit to New South Wales, Lightening Ridge, Coober Pedy, Queensland

Visit to a topaz mine in Brazil: Video (1.05 minutes)

Gem Inclusion Library

SORRY the Gem Inclusion Library is now OUT OF PRINT (2012).

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Gemlab Books and Instruments, a subsidiary of the Canadian Institute of Gemmology is the exclusive distributor of the “Gemstone Inclusion Library”; it contains 25 pages, 5.5″x8.5″, with 120 b&W line-drawings, 1 colour plate, CD-ROM disk loaded with over 100 JPEG picture files.

Cost is CAN$ 39.95

Background

The Gemstone Inclusion Library was published over 10 years ago and since then many new gem materials- genuine, man-made and/or treated have appeared in the markets. It would be an immense task to produce an updated Gemstone Inclusion Library and we simply do not have the funds and resources to do this; as a consequence the booklet is out-of-print and copies for sale are limited. However, 90 – 95% of gemstones in the market are those illustrated in the black&white drawings of the manual. The concept demonstrated is not antiquated but rather modern and innovative for serious gem identification today: IMMERSION.

Many gemmologists have never learned how to use this method effectively because it is messy and to work with a “dry” microscope is easier and much faster. But recent gem enhancements such as surface diffusion, bulk diffusion, beryllium treatments, etc can only be detected with the stone immersed. Amateurs use water and baby oil in an immersion dish; professionals use a liquid which is close to the refractive index of the stone to be tested. These organic liquids such as methylene iodide (the same liquid used in contact fluid for the refractometer), bromoform, benzyl benzoate and others may be available in your local drug store or from special suppliers. Afterwards the stones have to be cleaned thoroughly in neothene or alcohol because all organic liquids attack plastics and other surfaces.

Please go to The Appraisal Corner where you will find links to other websites with interesting inclusion images. For an inclusion glossary go here.

Gemstone Inclusion Library v1.8

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If you have purchased version 1.0 or higher of the Gemstone Inclusion Library you can now upgrade to version 1.8 below. Please note: The update only works with your purchased Gemstone Inclusion Library; it does not contain any images.

Gemstone Inclusion Library, Version 1.8 Update (Feb. 1, 2002) (update.zip, 34 kB)


Over 120 Black & White line drawings are used in the Gemstone Inclusion Library manual to illustrate typical inclusions in synthetic and natural gemstones.The enclosed CD contains 100 colour images of inclusions obtained from an immersionscope which can be viewed in a web-browser or printed out.

J. Wolf Kuehn, C.I.G. Director of Education, has compiled numerous inclusion pictures from the comprehensive study collection of the Canadian Institute of Gemmology. It is an ideal reference for serious gemstone identification. The guide contains 120 detailed line-drawings of typical inclusion features found in synthetic and natural gemstones; a diskette with over 100 colour micro-photos of inclusions (in JPEG and .htm format) is included. Most of the pictures were taken with an immersionscope (horizontal micsrosope) allowing the study of internal features with more ease and clarity. If a colour-printer is available high photographic quality can be obtained with special paper.

From the Author’s Introduction

After many years of teaching C.I.G.’s Gem Identification courses I felt that other students, practising gemmologists and appraisers might equally benefit from the various instructional materials used in the “Accredited Gemmologist” diploma program such as the Gemstone Inclusion Library.

When attending conferences, workshops and gem shows it was one of my most important tasks to look for new gem materials – natural, synthetic, invented, enhanced and/or assembled. Today I can state with great confidence that almost any possible gemstone encountered in the market-place is represented in the study collection of the Canadian Institute of Gemmology (C.I.G.); that includes natural gems such as Taaffeite and Benitoite as well as synthetic gems such as Knischka and Lechleitner rubies and emeralds.

During an evaluation of a gem or a piece of jewellery the most important part is the proper identification of the gem materials. In most cases this is a straightforward procedure; however, if the gem happens to be a ruby, sapphire, emerald, alexandrite or opal, it may require the microscope to study the internal features before deciding whether it is a natural or man-made product.

This is particularly true in the case of the latest flux-fusion and hydrothermal synthetic gems which include the Kashan, Knischka and Ramaura rubies, the Chatham, the Lennix, Biron and Regency emeralds and others. Most of us do not have access to more sophisticated testing equipment such as the electron microprobe or a Raman spectroscope. Our work must depend on the recognition of visual clues including diagnostic inclusions, colour zoning and growth patterns.

I wish to thank the Gemstone Training Centre Ruppenthal in Idar-Oberstein, Germany for their support in this project.

J.Wolf Kuehn, Director of Education, C.I.G.
Vancouver, B.C., August 1996

Die Welt der Edelsteine und Juwelen

Below are a few images obtained from a CD-ROM “Die Welt der Edelsteine und Juwelen” published by Koch Media GmbH-Austria, 1995 (the images are posted for educational purposes only)

m3 m1 m4
Liquid inclusion “trapped” in a topaz Crystal features under polarised light Heated air-bubbles moving in liquid inclusion

Animation 1: Air-bubbles moving around in crystal
Animation 2: Beautiful inclusion picture of topaz The bubbles are probably fluid carbon dioxide; see Inclusion Glossary below.

Inclusion Glossary

Inclusion Reference Library

  • Alexandrite, natural
  • Alexandrite, synthetic
  • Chatham Ruby
  • Chatham Sapphire
  • Emerald, natural
  • Emerald, Synthetic
  • Gilson Opal
  • Inamori Emerald
  • Kashan Ruby
  • Lechleitner Ruby
  • Lechleitner Emerald
  • Knischka Ruby
  • Regency Emerald
  • Ruby, natural
  • Ruby, synthetic
  • Sapphire, natural
  • Sapphire, synthetic
  • Lennix Emerald
  • Ramaura Ruby
  • Ruby Doublet
  • Sapphire Doublet

CIGem News Summer 2018

August 10, 2018 By Wolf Kuehn

Dear Friends and Colleagues,

We have updated our website GEMOLOGY WORLD for both the Canadian Institute of Gemmology (C.I.G.) and Gemlab Research & Technology. Designed for optimal user experience, the new site provides exceptional accessibility on devices of any size. Its focus on simplicity and modern-feel creates a smooth transition to bridge the gap from traditional desktops to mobile devices.

You can keep up-to-date on our Facebook pages for:

  • Canadian Institute of Gemmology
  • Gemlab Research & Technology
  • GL Gem Spectrometer
  • GL Gem Raman PL532

Please note in your calendar the following dates:

  • Advanced Spectroscopy Workshop, Vancouver, November 13
  • Advanced Gem Identification, Vancouver, November 9 – 13
  • Join us at the AGTA GemFair, Tucson, Feb 5 – 10

Gemology World Online Store

We have made some changes to our Conditions of Sale and acceptance of credit cards. At the bottom of the page we have added a section “Delinquent Customers” to protect our customers from fraudulent buyers who may attempt to resell our products. Presently we have a dispute with Desjardins Card Services which used to be our merchant bank for credit card transactions.

News from De Beers

Is De Beers’ Lab-Grown Line a Machiavellian Masterstroke?

Read this interesting blog at JCK’s website.

From Gemlab Books and Instruments

Diamond Handbook (3rd edition, 2018) by Renee Newman

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The 3rd edition of the Diamond Handbook (2018) updates jewelry professionals and serious diamond buyers on new developments in diamond grading, treatments, synthetic diamonds, imitations and fancy-color diamonds. Using close-up photos, it shows how to make visual judgments about clarity, transparency, brilliance and cut quality. Basic and advanced methods of detecting diamond imitations, treatments and man-made diamonds are discussed and illustrated. Tables, charts, diagrams and more than 350 photos are included making this an excellent reference on natural, treated and CVD & HPHT diamonds. Highly recommended book order here.

Growing a Diamond Using CVD: Video

Here’s some lab-grown diamond news that does not involve De Beers. Created diamond company Altr has released a 2 minute, 14 second video that shows how it grows diamonds inside its facility in India.

Watch it here (from National Jeweler).

GL Gem Spectrometer 2018 model

The new GL Gem Spectrometer has a modern modular design and faster microprocessor. With the new GLGemSpec software (version 3.3)  spectra can be saved and matched with the integrated fast search spectral library.  250 gem references cover Gemstones, Diamonds (incl. treatments) and PL405 spectra. There are now 300 GLGemSpec users in 35 countries around the world.

Perhaps now is the time to invest in a GL Gem Spectrometer; it is probably the most important low cost diamond testing tool as it is capable to detect the Cape lines (98% of natural diamonds are Type Ia), the GR-1 band of irradiated diamonds, the Si center often seen in CVD grown diamonds (in some cases without LN cooling), possible HPHT treatments, whether green jadeite is naturally coloured or spinel is synthetic or heat treated and much more.

SAVE US$ 2,000 and order DEMO GL Gem Raman PL535 TEC SOLD

This demo unit (2017 model)  has been used during trade shows and product demonstrations; the unit has been completely upgraded with new motherboard (version 3.x) and is in perfect working condition (regular warranty). With the new GLGemRaman software (version 3.1) spectra can be saved and matched with the integrated spectral library of over 300 gem references or imported into a separate searchable database program with over 3,500 edited references; this database is linked to the large on-line mineralogical RRUFF database for Raman spectra. There are already GL Gem Raman users in over 23 countries.

Long Term Viability of CZ Master Grading Sets

Interesting study and Photographic evidence of the long term viability of cubic zirconia for diamond color grading.

From the Insurance Institute of Jewelry Appraisal.

Gems & Gemology

Please download the Spring 2018-Gems & Gemology issue and enjoy.

Each issue is free and contains many articles of great value to gemmologists and users of the GL Gem Spectrometer and the GL Gem Raman systems.

 

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Gemmology is the science about gemstones. One of the objectives of this website is to provide gemmologists from around the world with an opportunity to exchange information in a fast and efficient way. At the same time Gemology World can serve as a resource for the general public to learn more about gems, diamonds and jewellery. Gemstones have intrigued mankind since early times in … Read More

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