Thursday, October 25, 2012
Okay back to the gemstone treatment issue. Today's topic is sapphires. First of all sapphires come in a wide variety of customers. I know that my customers are all aware of this because I have so many fancy color sapphires out, but if you've never been in my store and only been to traditional jewelry stores then you might not be aware of this fact. All of the colors of sapphires can be treated in some form or another.
The most common form of sapphire treatment on the market today is heat treatment. This is a process where the stones are put into ovens with controlled environments and baked for a period of time determined by the material being used and the desired results. Heat treatment is a process that changes the color of the sapphires, usually to a more "desirable" color (in blue sapphires this routinely means a darker color since that seems to be the most popular). This is a permanent color change and the stones never revert or change in color no matter what is done to them (recutting will not change the color). The industry likes to say that we're doing what would have happened anyway to the stones if they had stayed in the earth a lot longer (oh say a couple hundred thousand years), which is sugar coating it a little but, as I stated in my first article on the subject, man has been trying to improve everything around him ever since the beginning of civilization.
There are now some companies that only sell untreated sapphires and I sell both heated and unheated stones. With smaller goods it can be quite hard to know what you are getting because it simply isn't worth the time for anyone to check whether they've been heated, so normally I tell everyone that if the stone isn't certed natural, you have to assume it's been heated (which applies to virtually everything under 1 ct., as again, it's simply not worth it to check material in this price range). Occasionally, however, this isn't the case. I currently have a bunch of small orange sapphires that we know are natural because my dealers actually know the mine owner and this is his particular thing (not treating the gems that come out of his mine).
The more problematic sapphire treatment on the market today is called diffusion treatment. Diffusion treatment is a process in which they both heat the stone and diffuse a new element into the gems. The problems with this is twofold. With some diffusion treatment, the treatment is only on the surface so if you were to damage the stone and have it recut it would be a different color. Not long ago, however, it was also found that some diffusion treatments (specifically in orange and orange/pink sapphires) were actually going all the way through the stone. The second problem with diffusion treatment, in my opinion, is that you are actually adding something to the stone that isn't found in it in its natural state. Because of these factors I do not sell diffusion treated gemstones.
The good news is that diffusion treatment in sapphires can be detected by gem labs (at the moment---the illegitimate treaters keep trying new things so it's always a battle to keep up with everything). Most heat treatments are also detectable although the labs tend to err on the side of declaring stones heated even if there are only some minor hints at it (one of my dealers has had stones he knows to be natural come back with certs claiming heat treatment because the polishing process can create so much heat sometimes that it then appears that the stone has been heated).
These are the primary treatments for sapphires, although I once had a dealer try to sell me dyed material and I'm sure people are working on new ones currently. I know that I said I would talk about rubies in this article too, but I think I'll leave that for my next article as there are some real problems these days with ruby treatments.