Is Glass Filling the Answer for Low Quality Rubies?

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Discussion Overview

The discussion revolves around the treatment of low-quality rubies through a process known as "Glass Filling," particularly focusing on its implications for gemology and the stability of the treated stones. Participants explore the methods involved in the treatment, its acceptance in the gem market, and the potential issues arising from the treatment process.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes the glass filling process, including the use of hydrofluoric acid and heating with silicon powder, suggesting that this treatment improves the clarity of low-quality rubies.
  • Another participant notes that heat-treating gems is generally accepted in the market, as it can enhance color and clarity, but raises concerns about the materials used in the process.
  • There is a discussion about the differences between simple heating and more complex treatments that involve additives, with one participant emphasizing the potential toxicity of some materials used in gem treatments.
  • One participant questions why the treated rubies might crack when subjected to electrolysis, proposing that it could be due to differences in thermal expansion rates between the ruby and the filling material.
  • A later reply expresses agreement with the previous point about thermal expansion and stability, but does not provide a definitive answer to the cracking issue.

Areas of Agreement / Disagreement

Participants express differing views on the acceptability of glass filling and other treatments in the gem market. While some acknowledge that heat treatment is generally accepted, others raise concerns about the implications of using additives and the stability of treated stones. The discussion remains unresolved regarding the specific reasons for cracking in treated rubies.

Contextual Notes

Participants mention various treatments and their implications, but there are unresolved assumptions about the stability of filled gems and the effects of different materials used in treatments. The discussion does not reach a consensus on the safety or acceptability of glass filling as a treatment method.

mubashirmansoor
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Hello,

I am a student of gemology and just can't find a good explanation for the new "Glass Filling" treatment on Rubies, especially from Madagascar.

The following is a short description of how the treatment is done;

1) Ruby rough is dipped in Hydrofluoric acid for about 48 hours. This creates some holes, like very precise drills on the gem which helps to increase the clarity too.

2) The gem is placed in a heating oven for about 5 to 10 hours with an average temperature of 1800C.

3) During the heating process, Silicon powder is added all through the gems, which are somehow part of the ruby when its cooled down.

the silicon makes the very low quality rubies good for even jewelers that's why its becoming more & more popular everyday, although the treatment is not acceptable!


This Ruby has a massive practical difference compared to classical heating... It can't undergo electrolysis. If it is passed through electrolysis the stone is somehow cracked from the surface which makes it useless for jewelery.

Why should this cracking happen?

Any Help will be highly appreciated.
 
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This link will get you started:

http://www.ruby-sapphire.com/foreign-affairs.htm

Heat-treating many gems is acceptable to the gem market and is usually done to improve color. For example, Tanzanite rough is trichroic, but one of the three colors is a not-too attractive orange/brown. The market accepts heat-treating Tanzanite because it results in attractive dichroic stones with blue and purple colors. In this case you mention, the heating is done to fuse the fractures in the low-grade rubies so they will be clear enough to refract light when they are faceted. The fractures are filled with foreign materials that have a refractive index closer to that of corundum so that the filled cracks are less visible.
 
turbo-1 said:
Heat-treating many gems is acceptable to the gem market and is usually done to improve color.

Many Thanks for your informative link.

Yes you are right heating any gem is acceptable but as long as its considered as simple heating (adding nothing).

In gems treatment capital (Thailand) bulk diffusion gems are also considered as Heated and the vendors wouldn't say anything about it! Red Sapphires are an example... Sapphires just can't be red, due to low level of chromium. Beryllium is used for changing the color of white & pale violet sapphires from Songea (Tanzania) & Madagascar.

As you have mentioned gems are treated for a better look but that's just the good side of the story! The additives used are far more worse during heating stage; syonide, beryllium and many other highly toxic materials are being used that's why its not always acceptable! The classic heating is 100% okey.


The silicon causes the gem to break after passing an electric current, why is this?
 
mubashirmansoor said:
The silicon causes the gem to break after passing an electric current, why is this?
I don't know, but I suspect that it is because of a differential in the thermal expansion rate of the gem and the material used to fill the voids in the gem. If one material is more resistive than another, it might heat up more when you try to run a current through it. No filled/fused stone is going to be as stable and durable as one that is pure and solid.
 
Thats a very likely statement...

Thanks for that :) You have been a great help :)
 

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