"Lead glass filled Star rubies"

A selection of 34 lead glass filled star rubies showing the color range of the new material from pink to red and to near black. The stones presented weight from approximately 1 to 20 carats. The photograph was taken using a slightly diffused natural sunlight in Bangkok, Thailand. The background used is page 17 of “Gemstone Enhancement” by Kurt Nassau (1984).

Photo: V. Pardieu / GIA Laboratory Bangkok, 2010

Recently we were contacted by Mr. Mahiton Thongdeesuk, the burner who allowed me to witness his lead glass treatment process in 2004 in Chanthaburi :

Here are links to the article "Lead glass filled/repaired rubies" by V. Pardieu, then Director of the AIGS Laboratory in Bangkok published in February 2005 and its 2 updates published in "Gem Market News, a Supplement to The Guide" in July 2006 and September 2006.

This time Mr. Thongdeesuk told us that was about to release in the market some important quantities of lead glass filled star rubies and he would be interested us to study his material and inform the public about it as some stones were very much looking like fine unheated star rubies. So we studied these stones. It was a good occasion to show that gem burners and gemological laboratories like the GIA Laboratory Bangkok can work together. This update will we hope help to inform the market and the final consumer about these stones which if they are not a gemological issue are a serious problem for the trade.

Note about Lead glass filled star rubies: Lead glass filled star rubies are not a completly new thing, if fact the author saw some of them already in 2004 in Bangkok. They were first reported in the gemological literature by the GAAJ on their Jan 2005 update of the lab alert they did about this treatment on April 15th 2004. Recently an interesting study was also published by Thomas Hainschwang in his Gemlab Research Newsletter 06/2009 about lead glass filled star rubies looking quite similar to the lower quality material we saw at Mr. Thongdeesuk office. Is it the material studied by Thomas Hainschwang the same as the stones we studied? Difficult to say as many companies are producing lead glass treated stones nowadays on stones from different origins and using glass of slightly different compositions as the author already explained in his study published in February 2005. In fact there is not one treatment but at least as many treatments as you have companies. Furthermore sometimes the glass used by this or that company for this or that specific customer does not even contain lead but instead it is rich in bismuth or barium creating some terminology issues with the use of "lead glass filled rubies" in the case where lead is not detected. And of course it is clear that the treatment will continue to change as experimentation is still going on.

Summary about the whole "lead glass filled ruby" issue:

On the Gem lab side:

Lead glass filled rubies are very easy to identify for gemological laboratories. They were studied in details and a proper common nomenclature has been established by the gemological laboratories members of the LMHC group to identify them properly:

Here is a link to "A discussion on Ruby-Glass Composites & Their Potential Impact on the Nomenclature in use for Fracture-Filled or Clarity Enhanced stones in General" by K. Scarratt: "(April 01, 2009), this study about Ruby-Glass Composites was first released as limited LMHC (Laboratory Manual Harmonization Committee) distribution in Feb. 2008)"

Here is a link to the LMHC Information Sheet number 3, presenting the current nomenclature use by the six gemological laboratories members of the LMHC (listed by alphabetical order): CISGEM (Italy), GAAJ Laboratory (Japan), GIA Laboratory (USA), GIT-Gem Testing Laboratory (Thailand), Gübelin Gem Lab (Switzerland), SSEF Swiss Gemmological Institute (Switzerland).

On the market side:

Since 2004 when these stones arrived in mass in the market, many stones were sold without proper disclosure. If it was about heated vs unheated, that would have been without consequences but, unlike traditionaly heated stones, lead glass filled rubies present some serious durability issues:

Here is a link to the article "Identification and durability of lead glass filled rubies" by S.F. McClure, C.P. Smith, W. Wang, and M. Hall published in Gems & Gemology (Spring 2006)

Many stones were damaged particularly when jewelers were trying to use them in jewelry like if they were normal rubies. As the lead rich glass filling the fissures and the cavities can easily be damaged by chemicals like acids or caustic soda, by the heat of a jeweler torch and is also very brittle, many stones were severely damaged in the process. In consuming countries particularly where people are less aware of treatments, people feel to have been cheated. It created a bad name for the product.

Nevertheless as Tom Chatham said: “Gems do not cheat people, people cheat people”.

Sadly very often people buying or selling gemstones do not have enough gemological training to identify properly the stones they deal with. When in addition to that the stones are bought or sold without being properly identified by a gemological laboratory and without proper disclosure then this might not be without some serious consequences for the final customer and the trade when the stone present some durability problems like it is the case with filled gemstones.

That's the whole issue.

With proper disclosure and appropriate pricing, this material has its place in the market for the budget minded buyer who will never be able to afford unheated or traditional heated rubies. With lead glass filled rubies in fact such buyers have now an alternative to synthetics and imitations. Complete and accurate disclosure is the key to protect the buyer, and to build a healthy industry. So what to do?

Some people suggest that we should stigmatize this treatment and change the nomenclature on lab reports. Well, to the author understanding, the issue is not with the stones properly identified by gem labs, it is with the others. So changing the name on lab reports will not solve the trade problem, instead in the author opinion it might just add confusion. So in this case why to put all the gemological terminalogy upside down and take the risk to have a global confusion if it will not solve the main issue for the trade?

In the author opinion the terminology adopted by the gemological laboratories members of the LMHC and presented in the LMHC Information Sheet Number 3 is perfectly adapted to the current situation. With this this solid nomenclautre, what can lab gemologist do more to help the trade in this issue? Probably do our best to inform people about the treatment, publish informative studies like those the author recommend on this blog, remind people willing to buy gemstones that learning gemology can be useful, and if they don't want or cannot, then remind them that there are gemological laboratories who can do the identification work for them.

Hoping that you will find all that interesting and useful!

All the best,