The Quarterly Newsletter of the Canadian Institute of Gemmology (C.I.G.)
Another year is upon us: I would like to wish everyone the best for 2010. Without doubt there will be new challenges for gemmologists and the related gems and jewellery trades. The upcoming Tucson gem shows and conferences will set a good perspective for things to come. Let's stay well informed. Here a blog to Tucson Gem Show - Live! .
With regret I hear about the demise of Colored Stone magazine which had been publishing for over 20 years. With David Federman as editor-in-chief the magazine became a platform for all kinds of gem topics other trade magazines simply ignored.
I did not agree with Dave on everything he wrote; however, I appreciated him
for taking a position in the gem enhancement issues which helped to uncover the
andesine fraud and other still unsolved problems.
It will be difficult to find another independent journalist or publication which is more than ever badly needed for the gem industry. Colored Stone magazine will be missed by many.
The discussion about filled rubies is continuing. It appears that in certain circles of the trade the gem dealers' interests are given priority because they want to sell these materials as "ruby". It is unfortunate that consumers have been lured into buying these stones set in jewellery for hundreds of dollars without realizing of what they were buying.
A trained gemmologist can identify the various types of filled rubies; the newer types may not contain the obvious gas bubbles. The starting material for much of the "glass filled" or "composite" ruby is worthless highly fractured corundum which had been cleaned. The resulting cavities are then filled with glass compounds to resemble the appearance of ruby. If selling this material advise must be given how to handle the jewellery when cleaning, etc. because the filler easily disintegrates.
The "filled rubies" I have inspected since my visit to Chanthabury, Thailand DO NOT show the properties of a "single crystal" material rather those of an "aggregate": under the polariscope this material remains bright while being rotated. So far I have not seen filled rubies (as shown above) which clearly show the refractive indices and bi-refringence pattern (under crossed polarizers) one does expect from a "single crystal" gemstone.
I personally advise jewellers to stay away from heavily filled gemstones of any kind due to the unknown stability of the material. I also discourage to name this type of material "ruby" because it is a "man-made" product and in many cases there is more glass or filler material than corundum substance. I have suggested to name this material "ruby enhanced glass" though some people prefer a trade name which retains the designation "ruby". Ask yourself: Do you buy a bottle of red wine labeled "Pinot noir Reserve" when 20% water had been added?P.S. Be aware of Lead Glass filled Star Rubies from Madagascar; see study and report from GIA Thailand.
Fillers are being used in gemstones when fractures reach the surface of the gem. Jamey Swisher from GemAddicts reports about some tests done to proof the treatment of a garnet; see Clarity Enhanced Garnets. The article describes how the filler in a hessonite garnet was removed using a solvent.
The left image shows the partially filled fracture and on the right the partially dissolved filler.It is important for gemmologists to keep up-to-date with this type of treatment. It is expected that fillers will be used in other gems similar to the "filled rubies" and "Gematrat" treated emeralds.
During my recent trip to Guatemala I visited the premises at Jades S.A. in Antigua. I want to thank the staff for telling me the story about Guatemalan jadeite. Geologist Jay Ridinger discovered the Olmec Blue Jade in 1975 (he passed away in 2009). His archeologist wife Mary Lou and family members continue with the enterprise. Their showroom which is both a factory and museum is located at #34, 4 calle oriente, Antigua and a must for jadeite lovers. Visit their website. Also read my travel documentary "Search for Jadeite in Guatemala".
The images above show samples of Guatemalan jadeite; the image on the right is from a display case at the museum in Ruinas de Copan, Honduras.
The left image shows how garnet was used (as it was explained to me) in carving the tough jade material; the right image displays the interesting colours of a thin plate of jadeite held against a light source. So far Guatemalan jadeite has not been treated.
Recently several interesting pieces of equipment and gem materials were donated to the school. On the left shown is an almost mint "Gemmological Microscope" made by Rayner; it was first introduced in the Journal of Gemmology, Vol. V, No. 1, 1955; read here. I wonder how many of these units are still around. The next image shows the Rayner Prism Spectroscope with adjustable slit which can be used with the microscope.
Using the provided light source (with ancient power supply!) I was able to see three-phase inclusions in a Colombian emerald without difficulty - truly an amazing piece of equipment which came in a mahagony case containing numerous accessories.
To the right the almost forgotten original Rayner refractometer with the monochromatic sodium light source - still in perfect condition.
I would like to thank the Brierley estate for this generous contribution.IMPORTANT RED ANDESINE UPDATE: Contrary to the unfortunate publication in a renowned gemmological journal about Tibetan natural red andesine there has not been any independently confirmed mining source for this material. According to Dr. George Rossman (California Institute of Technology) who has studied feldspars for over 20 years "none of the stones from Tibet (or those claimed to have come from the Congo)....(that were obtained from either people who say their family owns the mine or from people who have visited the mine)" proved natural red andesine. See The Red Feldspar Project.
More about it at The John Sinkankas Feldspar Symposium - 2010.
In this course you will learn everything you need to know about diamonds. Sell more and answer customer questions with confidence. Introduction to diamond grading and jewellery fashion.
Course Content: 1. Diamonds. How they are created. 2. The Beauty of Diamonds 3. Weight and Colour of Diamonds. 4. Judging the Clarity of Diamonds. 5. Judging the Cut of Diamonds. 6. Diamond or Imitation? Gold, Platinum. 7. Choosing an Appropriate Style. 8. Choosing a Diamond Ring, Judging Craftmanship.
In this course you will learn about pearl types and shapes, how to judge luster, thickness, colour and size of pearls. The identification and evaluation of South Sea, black and freshwater pearls and other organic gems are also covered. There will be one session on opal and its evaluation. Another session will cover the jades - oriental jadeite and nephrite.
For more information about Vancouver courses go here.We have reduced the price for several books to clear our inventory. Go to Specials or visit Books and Instruments.
Past issues of C.I.Gem News: Click on the edition you want to read:Special GIT 2008 edition - Spring 2009 - Summer 2009 - Fall 2009. The next newsletter will be published March 23, 2010.
To subscribe other interested people to CIGem News send an email to CIGem News
We will never use our subscriber e-mail addresses for anything but our newsletter. To UNSUBSCRIBE to our newsletter, click HERE
Unless indicated otherwise images © 2010 J. Wolf Kuehn and Canadian Institute of Gemmology. Users may View/Download images for their own private, non-commercial use.
The articles in CIGem News express the opinions of the editor and do not necessarily reflect those of the Canadian Institute of Gemmology (C.I.G.). The included links are provided for educational purposes. Copyright and content responsibility remains with the linked organization and do not represent any endorsement by the author. The designation ACCREDITED GEMMOLOGIST (C.I.G.)® diploma is a registered certification mark (see Industry Canada, Canadian Intellectual Property Office) and requires a user license for business use.