The subscribers' page and the nerve-centre of Organic Gems. In Forum we exchange comments, queries and research, answer the subscribers' questions and publish the latest information available.
(The following article is from the online archive/magazine, 'Organic Gems')
This section of ‘Organic Gems’ belongs to the readers. Subscribers to the periodical are invited to contact the editor with any questions or comments concerning the articles that have appeared in the periodical. News, information and general questions on organic gem materials are also welcome. Subjects raised will be researched where necessary, and results will appear in following issues of the periodical.
The editor regrets that it is not possible to answer all e-mails personally.
In the absence of readers’ comments for the first issue, we covered a couple of items of current interest. These have since been updated in later issues of Organic Gems.
COPAL IMITATING AMBER
Copal resin, which could be described as young, immature amber, has for a long time been used to imitate the more mature material. Copal is typically a few thousand years old, while amber is several millions of years old. Being less mature, copal is not as durable as amber.
A few years ago we heard that copal was being heat treated in an autoclave to ‘turn it into amber’. The early results were less successful, but recently some very convincing material has appeared on the market. At present it is being sold as treated copal, but it can only be a matter of time before it is sold by the unaware or unscrupulous as ‘real amber.’
Pieces of this material have been tested by infra red spectroscopy, and give a result typical of copal. However, the experts running the tests were quick to admit that, if they had relied on visual examination only, it would have been very difficult to see that the material was not amber.
A future Organic Gems article will compare the properties of amber and copal.
TERMINOLOGY
There are many incorrect and misleading names in common use in the gem and antique trade. ‘Forum’ will endeavour to bring these to light and correct them, in an effort to give more clarity and prevent misunderstandings.
All corals are animals -- none are plants -- but the misconception persists amongst many. This is not helped by using names such as ‘vegetable coral’ for some black or golden corals. Can anyone enlighten us on the origin of the term ‘vegetable coral’?.
Another misleading term is ‘staghorn’. Members of the family Cervidae -- e.g. various deer, elk and moose -- carry antlers, which are a very fast growing form of bone. With the exception of reindeer and caribou, only the males – i.e. the stags – carry antlers. Horn, on the other hand, is a totally different material consisting mostly of a protein called keratin, and usually carried by both sexes of the family Bovidae, e.g. sheep, cattle, and antelope. Can anyone enlighten us on the origin of the term ‘staghorn’?
The various gem corals, will be covered in later issues of Organic Gems. Articles on horn appear in Issue 4.
SOME SUBJECTS NOW BEING COVERED IN SUBSCRIBERS' FORUM
- Updates on 'cherry amber' and amber dyes.
- The true cause of colour in pearls.
- A curious amber necklace -- natural or treated?
- Updates on copal treatments.
SUBSCRIBERS' ISSUES OF ORGANIC GEMS
'Organic Gems' deals with all the aspects of the fascinating materials known as organics, including amber, copal, jet, ivory, bone, antler, horn, rhino horn, tortoiseshell, pearl, shell and coral. Lesser known materials such as shagreen and vegetable ivory are also covered.
Future guest authors will include:
- Jill Darrell, Curator of Corals, Department of Palaeontology, The Natural History Museum, London
- Ian F. Mercer, Director of Education, Gemmological Association of Great Britain
- Dr. Jack Ogden, Chief Executive, Gemmological Association of Great Britain
- Christie Romero, Director, Center for Jewelry Studies, USA
- Dr. Brian Rosen, Research Associate, Department of Zoology, The Natural History Museum, London
- Dr. John Russell, Chairman, the Plastics Historical Society
Issue 2, March 2007. Articles include: A background to bone and antler; a look at shell and its many uses; and guest author: Gail Brett Levine, GG, Executive Director, National Association of Jewelry Appraisers, USA.
Issue 3, May 2007. Features include a background to tortoiseshell, a write-up of the March 2007 amber fairs in Gdansk, Poland, and an article, 'Baltic amber - enhancements, treatments and their effects'. Guest author: David Lancaster, FGA, DGA, formerly Director of Christies, London.
Issue 4, July 2007, includes articles on horn and Burmese amber. Guest author: Adele Schaverien, formerly archivist and keeper of the collection for the Worshipful Company of Horners, London.
Issue 5, due out late September 2007, will include an article on pearls. Guest author: Christie Romero, Director, Centre for Jewelry Studies, author of 'Warman's Jewelry'.
What's in all the issues of the online archive/magazine? Go HERE to view the full list of contents.
