Friday, December 01, 2006

Boldly Going Where No Lab-Rat Has Gone Before

Lab Games Part II

Gem Science: Playing Catch-up:

In a very informative post on Gemologyonline.com Vincent Pardieu former Director of the AIGS gem laboratory in Bangkok tells a interesting story:

In 1995, a man from Chanthaburi, Thailand who specialized in heat treating yellow sapphire discovered that he could dramatically improve the color by using a powdered form of a mineral known as ploy nua oon in the Thai language. In 1999 when a new strike of pink and yellow sapphire from Ilakaka, Madagascar started entering the market he found that by using the same method he could turn the pinks an attractive pinkish orange or padparadscha color. http://gemologyonline.com/Forum/phpBB2/viewtopic.php?t=679&start=30

"Ploy Nua On" is the Thai name for a stone known in English as chrysoberyl. The burner just discovered in 1995 how to use a beryllium rich atmosphere to lower the blue content in sapphire and create in some cases an additional yellow color and by 1999 the first Beryllium treated padparadscha were in the market. .The dreaded Beryllium diffusion treatment was born.

What is Beryllium diffusion and how does it differ from plain old heat treatment? The key word is diffusion, a foreign element, beryllium is added to the stone. With traditional low-temperature heating nothing is added. This type of heat treatment has been going on for several thousand years. High temperature heating began in the 1970s and does actually involve hydrogen diffusion but on grading reports it is typically called “heat only” , has been accepted as “traditional” by the market and has dramatically less effect on price than Beryllium diffusion.

The AGTA laboratory put out a warning in January, 2002 http://www.agta.org/consumer/gtclab/orangesapphirealert.htm just before the big Tucson shows but it was not until the September 2003 Hong Kong show the full impact of this treatment hit the market. Sapphire prices dipped 20-40%. I recall dealers running for the hills willing to unload treated sapphire at almost any price. Were all these stones beryllium treated? No one quite knew.

This is a perfect example of the catch-up game that gemologists must play. Technology improves, new treatment methods are discovered by accident or on purpose and the laboratories first must determine that something is being done and then what is being done. In this case with a time lag of seven years.

Boldly going where No Lab-rat has gone before.

Gemological Laboratories are under increasing pressure to add quality grading to their traditional role of determining origin and treatment of gemstones. One laboratory, AGL had been doing this for several years. However, recently under the aegis of the Lab Harmonizing Committee several of the leading labs have decided to aggressively go where no lab has gone before into the world of marketing. Gem Labs have entered the nomenclature business and into a firestorm of controversy .

The question of nomenclature is often more about tradition than science. You can study internal inclusions and make a determination about treatments and point out what specific anomalies led to your conclusions but how do you decide what to name a gem? The recent flap over Mozambique cuprian tourmaline that I covered in an earlier post is an excellent example. http://gemwiseblogspotcom.blogspot.com/2006_06_01_archive.html

Traditionally we name a gemstone based on species and variety but what happens in the case of a gem that is of the species corundum but derives its name strictly from a mix of colors? What gem am I thinking of? I’ll give you a hint; padparadscha sapphire.

In my book Secrets Of The Gem Trade, The Connoisseur’s Guide To Precious Gemstones, www.secretsofthegemtrade.com, following the late great GIA gemologist Richard Liddicoat, I define padparadscha as a light to medium tone of pinkish orange to orangey pink. Up until recently, labs have avoided the issue by simply calling the colors; “pinkish orange” and so forth.

A consortium of gem labs under the title: The Laboratory Manual Harmonization Committee (LMHC) met in Milan and has drawn up a standardized definition of padparadscha. The LMHC consists of seven of the world’s major laboratories (AGTA Gem Testing Center, CISGEM (Milan), GAAJ (Japan), GIA (USA), Gemological Institute of Thailand, G├╝belin Gem Lab (Switzerland) and SSEF Swiss Gemmological Institute (Switzerland). Some of these labs, excluding for the moment GIA-GTL, have begun to call and consumers have begun to demand a lab certificate that uses the term padparadscha to describe the stone. The question is, where is this definition coming from and is this the beginning of a brave new world wherein laboratory gemologists begin to dictate to dealers and connoisseurs?

“Well”, I can hear you say, “somebody’s got to cut through all the confusion.” and I agree. But, be careful what you wish for. Leaving aside the question of how this definition was arrived at, like it or not, once established the criteria determined by the labs will become the accepted definition. Are we ready for this and what in the training of a gemologist prepares them for this role? I received my Graduate Gemologist diploma some years back and I can tell that what a neophyte Graduate Gemologist doesn’t know about quality in gemstones would fill many volumes. A newly minted G.G. is little more than an apprentice scientist. Oh sure, he learns the GIA diamond grading system but…

According to Richard Hughes well known author and gemologist with the AGTA gem laboratory which makes him one of the most prominent lab-rats, laboratories have no business making such calls. He was particularly upset by the fact that the LMHC did not include a representative from Sri Lanka at the meetings where the decision was made (I mean where does the term come from?). Hughes also had problems with the adoption of a printed color chart developed by Franck Notari (GIA Geneva). Hughes makes the point that the definition of padparadscha is fuzzy at best and he feels that the insistence on hard a fast definitions is not appropriate. As proof of this assertion, Hughes did an analysis and discovered that the magnificent 20.84 carat padparadscha (pictured above left) that sold last year at Christies falls outside the parameters as defined by the chart adopted by the LMHC.

Stay tuned…

If you are in our neighborhood mark your calandar: December 23rd at R. W. Wise, Goldsmiths: The Magnificent Jewels of London designer Stephen Webster, 10am-7pm. Webster is one of the most influential new designers. All his work is made in London by Goldsmiths and besides being exquisite it is also very well made. Previews can be found at http://www.stephenwebster.com/


I get emails but no comments!

This blog gets a lot of readers but I am disapointed by the lack of comments. Am I preaching to to choir or are there people who strongly disagree? I realize that a good many of my readers are magazine writers, clients, collectors, editors and gem and jewelry lovers not working professionals. Seems to me that the lab issue is one that dealers, gemologists and students of gemology would want to think about. Imagine a world in which everything from the grandest ruby to the humbalist garnet has a certificate that tells you all about it, everything including how good it is.

Perhaps you don't comment because you are looking for a job in a gem lab and you know that the net is a little like the difference between true love and herpies. The desease and the internet are forever.

The speed and ease of the internet make it so easy to communicate that sometimes you end up disagreeing with yourself. In the "good" old days published opinions were considered final. Today they should not be so considered. I think of my posts to be an intellectual work in progress. I claim the right to change my mind. So, please, comment away, I welcome your input.

5 comments:

EileenAZ said...

I don't comment because I don't know enough about gems to speak with authority. However, I'm thrilled to have found this forum- I've been looking for something like it for years. I'll be lurking whether or not I comment on your weblogs. I live in Tucson and have been attending the gem shows since I was little (and the Tucson Show was little, too).

Anonymous said...

Richard, thanks for the post. Like Eileen, I don't post as I am a novice . I collect rocks and in some cases heat them for color and to mount. As far as commenting on a statement of events or contravention of personal opinion, I am not knowledgeable enough for that. What I will say is thank you for taking the time and expense of providing this for the 'oh so many lurkers' such as myself.

Terry

aligirl712 said...

Mr. Wise
I have a question that you may have somekind of answer to this new andesine/labradorite. Has anyone found out any other information on its origin or even is it treated. It seems to be such a mystery. (maybe they want it to be that way for value adding purposes) I have done research on it and have not found much. I thought that you may have heard anything on this subject? It is so unusual.

As always thank you for your precious time.

I always enjoy visiting your site. You always the most interesting reading around.

your biggest fan.

alice

Paul_S said...

Hi Richard,

As you stated, the finest 'Pad' you have seen came from Songea, Africa. As an East African Prospector/Dealer there is no argument from me. I have seen literally tonnes of Sapphire from the Umba and Songea. A good East African Pad to me is quite a common occurrence. I see them all the time in river material. Many match the Sri-Lankan stones in colour and many are superior. I have seen so many 'Pads' from the Umba, in my own mind they are no longer the rarity they used to be. The consumer must remember that Asian Buyers are everywhere in East Africa waiting to pounce on these stones. They are then taken back to Asia, faceted and then released to the world market. I know from the current ratio I have personally witnessed that many are being sold after cutting as Sri-Lankan stones.

I believe we have now have saviours with such techniques as LIBS and I use the set-up at the Australian National University as often as possible. This could even mean Fraud charges for unscrupulous dealers who give false origins for stones in an attempt to push the price up for their own gain.

The new laser techniques can establish origin of stones by matching trace elements from stones previously tested from a locale.

Richard, I was also wondering if the Golden/Orange Corundum that colour-shifts to Ruby Red from the Rift Valley Area has been given an acceptable name yet? Originally, some gemmologists in Australia stated they were synthetic but could not offer any Gemmological reason as to why they thought that apart from 'They are too clean"! This is even after the had been examined rough with host still attached to it. When tested at the ANU they were matched to Corundum from the Rift Valley area. They have Ni2+ and Mg2+ acting as chromophores, but also have 40-60ppm Chromium content which, as you know, means they should be Red. However, it is believed that the Ni2+ is acting as a masking agent. Indoors and under artificial lighting this masking effect weakens and the Ruby colour comes to the fore.

Paul

Richard W. Wise said...

Paul,

Very interesting comment and informative comment.

I am ashamed to say that the Rift Valley color change corundum that you are describing is new to me. I have never seen an example. Any chance of an image?

You can email me at richard@rwwise.com. Please do I would very much like to communicate with you.