Rubies are a form of corundum, which is the same material that sapphire is. The only difference is that it has to be red to be called a ruby. There is a fine line sometimes between ruby and pink sapphire, but a lot of rubies, especially Burmese material, will have an element of pink in them. Rubies are also one of the rarest forms of corundum, and as such, carry a much higher price tag then sapphires do, if the quality is equivalent (in other words there can be junky rubies much cheaper than fine sapphires). Unfortunately because of this ruby treatments have become more of a problem than sapphire treatments in the trade.
Most major gem labs are now giving different treatment grades to ruby based on how aggressively rubies have been heated. When rubies are heated, especially rubies with significant inclusions, flux from the heating process often enters the stone, and when the flux hardens it becomes glass. This often means that there is glass inside the rubies. When rubies are aggressively heated--something being done particularly with very low quality material that is very heavily included, more flux gets into the cracks and forms glass. A few years ago, the director of one of the leading gem labs at the time came out with a statement saying that it had become unclear in some of these aggressively treated rubies whether the proper description should be ruby with glass in it or glass with ruby in it as so much of the stones were made up of the flux material.
The GIA currently uses a seven level grading system regarding heat treatment in rubies: NTE (no treatment) and then TE and TE1-5 with the increasing numbers indicating increases in flux residue. Obviously when you hit TE5 you're in that zone where it's really pretty unclear what you are getting. Personally I wouldn't sell anything higher than a TE3 as beyond this it's my belief that the level of treatment has been too aggressive.
There is also an argument running in the trade right now (I think I may be a lot of the cause of it) about disclosure on ruby treatments. The Jewelers Vigilance Committee (JVC), a group formed to act as an industry policeman, currently claims that in most ruby treatments, disclosure is not necessary. They base this on what I perceive to be a flawed argument, that there is simply so little unheated ruby material available that it isn't necessary as no one could purchase unheated material (this IS a valid argument in the case of something like tanzanite, a material that wouldn't even be sold were it not for heat treatment and in which 100% of the material is heated). However I am able to source unheated ruby material and feel that this is a specious argument, mainly based on their collusion with larger manufacturers in the industry who don't want to deal with the disclosure issues. The AGTA, another industry self policing organization, of which I am a member, does mandate disclosure of all ruby treatments. When the new superheated ruby material came into the market, the JVC suddenly found itself in the position of having to reverse its prior statements about nondisclosure because the superheated material has durability issues and also is so beyond the norm that they were forced to issue changes in their disclosure requirements.
So what is a customer supposed to do? Well, as I always tell people, know your sources. If you are buying online, you will never really know who you are dealing with so I always recommend purchasing things like this from somewhere that you will have recourse if something isn't what is is supposed to be. Secondly, if you see someone selling a 1-3 ct. ruby for under a few thousand dollars you can be pretty much assured that this is some of the aggressively treated material and you should stay away from it, not just because of the fact that you aren't really getting ruby but also because there are durability issues with it. While with smaller goods, there is no way around getting heated material (no one even bothers to check most of the time as it simply isn't worth it), if you are investing in a reasonable sized stone (1 ct. or above), ask for a stone with a certificate so you can at least know how heavy the treatment is. If you really want a natural, unheated stone it is absolutely mandatory the stone comes with a gem lab certificate. The material is out there, but you should be prepared to pay a price for it. A few years ago, a collector was in looking for a 2 ct. natural, unheated ruby and I got 6 stones in for him. They ranged in price from $8000 to $120,000. The $8000 stone was ugly as all get out. Once you got up into the $30,000 range they got much better looking.
Remember if it seems to be too good to be true it probably is. But this is a caveat that you should take into consideration when buying any product that you don't know that much about. In my next article I will get into a variety of other colored stones and their treatments.
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