a publication of the International School of Gemology 10.July.2013

Identifying Lead/Cobalt Sapphires

ISG works to de-mystify gemstone treatments...

Stop for a minute and look at the sapphires in the banner of this edition of our newsletter. Blue sapphires. Very pretty blue sapphires. Very affordable, pretty blue sapphires. Very affordable, pretty blue sapphires that have been color infused using a new cobalt and lead treatment developed by Ted Themelis. This treatment turns previously unusable corundum into marketable blue sapphires to help ease the burden of dwindling supplies amid growing demand for gemstones. Simply stated: Without gemstone treatments we are going to run out of products to sell. No products = no profits = we are all flipping burgers at the local burger joint. The key issue is the ongoing commitment of Ted Themelis and others to provide proper disclosure and identification information that will help us de-mystify this new treatment to consumers and help turn this material into a viable revenue stream. In short, it will help us do more business in the future. Here is how to identify this new treatment and the new blue sapphires it produces....

At left you see the type of corundum crystals that are used for this treatment. Not all crystals react to the treatment but those that do can produce some very nice blue sapphires. This material would otherwise be dumped out or used for powder, but with the research of Ted Themelis and his group this otherwise unsalable material is turned into the blue sapphires you see in the banner at the top of this page.

Below left is one of the oval sapphires from the banner that has a light blue or "cornflower" type of color. Below right is a 10x image of this showing the internal structure created by the treatment that makes for easy identification of blue sapphires that have been treated by this method.

At left is a 60x image of the internal structure showing patterns that some say appear like a hydrothermal growth structure, which when compared to hydrothermal grown sapphires in our ISG Student Reference Collection does bear some resemblance. However, given the other features of gas bubbles that closely emulate those found in lead glass treated rubies, the identification of these specimens as cobalt/lead infused sapphires is unmistakable.

Below is the round blue sapphire the exhibits the well-known flattened gas bubbles that are often seen in the lead treated rubies. This feature has become quite diagnostic for this type of leaded treatment as the process allows some gas to enter the stone leaving some specimens with a significant amount while others may have very few.

Below is a 60x view of this stone using our Meiji Techno GEMT-5BFDF microscope to clearly capture the hazy infusion material and the gas bubbles in this sapphire.
And finally is the view below, also at 60x, showing the color infusion patterns that are often seen in these sapphires and in treated rubies.

Other identification methods:

Chelsea Filter: One of the fastest and easiest methods to identify the cobalt/lead sapphire is by using the Chelsea filter. The cobalt gives a strong red reaction to the Chelsea filter as seen in the cobalt colored lab created spinels. This is a diagnostic test that can be done quickly at a gem show or gem dealer office to confirm the status of the sapphire.

Spectroscope: Since cobalt has a unique three-band absorption spectrum it would be assumed that this would also be a diagnostic test. However, using our OPL hand-held diffraction grating spectroscope, the GL Gem Spectrometer, and the MDM Spectrometer we found that the anticipated absorption lines to be very faint, owing to the relatively small amount of cobalt used in the process. As a result, while the Chelsea filter proved very valuable for grass roots level dealers and gemologists, the spectroscope was less successful, due to low cobalt content, in providing strong evidence of the treatment.

All other tests showed classic corundum results with no significant signs that would assist in identifying a treatment.

With proper disclosure, this new development in the production of treated sapphires is an important step forward toward this industry having enough product to sustain market demand. We must have gemstones in order to maintain this industry. The answer is not to start creating mythical mine locations in far off Tibetan deserts to fool consumers. The answer is to raise the level of awareness of, and to de-mystify, gemstone treatments that can utilize a greater amount of gemstone mine production for commercial purposes.

Thank you to Ted Themelis and Tom Chatham

We wish to acknowledge and express our appreciation to the long-standing work of Ted Themelis and Tom Chatham to bring some common sense to this industry regarding treated and created gemstones. These folks have worked for years, without much real credit, to get our industry to become aware of the need...the absolute need....for treated and created gemstones for the future of the industry. Today, that need is starting to hit home and we need to all take a very serious look at what they have been telling us for years. Without treated and created gemstones we will run out of product to sell.

Without product to sell....well.... "Do you want that burger with french fries or onion rings, Ma'am?"

We all better learn how to say that if we are not willing to adopt and embrace treated and created gemstones.

Ted Themelis...well done! Well done, indeed! We love these sapphires!

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