Heat Treatments in Rubies & Sapphires

A Note about Disclosure

Consumers are rarely told that this ruby has been heated above the melting point of steel and thus is a hundred times less rare that a natural ruby of similar appearance. Nor do many explain to the retail customer that a yellow sapphire was manufactured from nearly colorless low-value corundum via beryllium diffusion. What might be the value of a heat-treated sapphire if a consumer had a full understanding of these realities? Would he or she be willing to pay a hundredth the price of the natural sapphire, a tenth, a third, or more? We simply don't know. What about stones manufactured by beryllium diffusion? What would happen to values if the arcane knowledge of treatments became public? To date, few customers have been offered an honest description of treatments at the time of purchase. Who knows what might happen if they were?

We have provided information on this page with the sole aim of making our customers aware of the treatments performed on rubies and sapphires before they make a purchase. We, at The Star Ruby Shop, support only Natural and Untreated Gemstones and hence we do not sell heated, lead-filled, recrystallised, flux-filled, diffused, beryllium treated or synthetic gemstones. Whatever may be your preference, please emphasize on certificate from a reputed gemological laboratory to confirm the natural origin of any gemstone you purchase and to be sure that no treatments have been performed on the gemstone.

Classifications of Heat Treatments

Heat Treatments without additives

Gemstones subject to heat treatment without additives command a higher price than those with any other treatments, though much less than natural, non-treated rubies and sapphires. In case of heating without additives the main emphasis is laid on the conditions at the time of heating and the temperature. Sapphires are generally heated in reducing environment while rubies in an oxidizing environment. Heat treatment without additives is generally more accepted than any other form of treatments.

Heat Treatment with additives

Lead Filling: During this treatment, rubies are infused with lead crystal glass of high refractive index. The result is that nearly opaque stones turn to transparent or near transparent. However, this treatment is not permanent and many a times, lead-filled rubies get damaged during setting or mounting in jewelry. Today, lead filling is generally not accepted as a treatment because of the toxicity of lead during the heat treatment and due to its non-permanent nature. Rubies enhanced by Lead-Filling treatment are available in huge quantities and hence can be purchased for dirt-cheap prices.

Recrystallisation:  In this treatment opaque or very low quality sapphires and rubies are treated in a series of steps to recrystallize them and increase their transparency. Generally the steps involved are very long but at the end the material is completely different from what it was at the start. Gemstones treated using this method also fetch lower prices, comparable to those of lead-filled rubies and sapphires.

Beryllium treatment: The beryllium treatment is more of a discovery than logic. The story behind this treatments is as follows. A Thai treater was heating pink sapphires and by mistake a piece of Chrysoberyl went into the furnace along with the sapphires .When the treatment  was completed he was astonished to see the color of sapphires changed to rare padparascha color. This led to the start of a new treatment called Beryllium treatment. Beryllium, when added in very small quantities during heat treatment, can change the color of sapphires greatly. As a result of this a Sapphires of various colors are available in the market which are the result of heat treatment by beryllium process.

Flux Treatment: In this treatment various additives such as borax, sodium carbonate, sodium silicate and many other natural minerals and lab made chemicals are added for various specific improvements in the rubies and sapphire. Flux filled rubies are generally more accepted than lead-filled or recrystallised rubies. This treatment was majorly done on the Mong-Shu rubies from Burma.

Surface Diffusion: Surface Diffusion treatment is performed on Opaque or weak-colored rubies and sapphires . By diffusion, a thin coat of color is coated on the gemstones due to which the gems appear to have a great color. However if the stone is recut or even scratched, the coating goes away revealing its true color. Diffusion-treated rubies and sapphires are available for extremely low prices and are normally not very much accepted.  Sometimes rubies and sapphires are coated with titanium dioxide which causes the formation of 6-ray or 12-ray star on the surface when viewed under the sun. These are normally called Diffused Star Rubies / Sapphires or Diffusion Treated Star Rubies / Sapphires. Diffusion Star Rubies & Star Sapphires are similar to Natural Star Rubies & Star Sapphires, only that in case of diffused stars, a scratch on the surface would totally damage the gemstone.

Heat Treatment on Synthetic Rubies & Sapphires

Synthetic rubies and Sapphires produced in a laboratory by artificial means are sometimes heat treated to improve color, luster etc. These synthetic stones can be easily identified in a Gemological Lab.

Unheated Rubies from Burma  |  Unheated Rubies from Madagascar  |  Unheated Rubies from Mozambique  |  Unheated Rubies from West Africa  |  Unheated Sapphires from Burma  |  Unheated Sapphires from Ceylon  |  Unheated Sapphires from Australia