5.10 Ct OVAL CUT TOP NATURAL RICH RED RUBY

PLease take into account that these photos are a 10x enlargement of the stone and that inclusions are amplified. The stone is really spectacular!

Sometimes a ruby will have dense silk clouds and a strong purplish color, making the stones look like low-grade, cloudy rhodolite garnet. This is mainly due to the crystal's unusual blue cores. Ordinary heat-treatment removes the blue, as well as removing silk, making the final product a rich, clear red. The market generally accepts such heated stones without a quibble.

Some rubies are heavily fractured and Thai burners have combated the cracking by healing the cracks with a flux such as borax. Heating the stones with borax and other chemicals actually melts their surfaces, including the surfaces of cracks. The corundum within this molten material then redeposits on the fracture surfaces, filling and healing the fractures shut. Undigested material cools into pockets of flux glass. Essentially this amounts to a microscopic deposition of synthetic ruby to heal the cracks closed. This treatment is permanent and irreversible, the remnant pockets of flux will not drain out in the future, nor can they be removed.This treatment actually improves a stone's durability, since the fractures are healed shut. In many respects, it is a welding of fractures, similar to the joining of two pieces of metal with heat and a flux to lower their melting point.

The thing is that nearly all rubies in Thailand show some residues so we must assume they have been flux healed. The amount of residue in the ruby determines how little or many cracks were healed. If there are 'residues insignificant' then there has been very little healing, if any at all.

The term 'glass filling' is very misleading as many 'chemicals' are added to the heating process, and the folk who do the treatments are extremely secretive about their process. This has created a very real problem, where the enhancement is generally accepted by Thailand-based dealers/gemologists, but rejected by those outside the country. The result is that goods are returned amidst much name-calling and hand-wringing, a situation from which only lawyers will benefit. Compounding the problem is the fact that laboratories around the world do not have uniform methods of describing or dealing with this enhancement. Some cannot even properly identify it or distinguish between naturally-occurring inclusions and the flux healing.

My own opinion, for what it is worth, is that if the changes are permanent and the ruby is clear with good color it certainly worth collecting. As to the cost; a 2ct. unheated, clear ruby might fetch $10,000 per carat whereas ruby of similar quality that has been treated might be purchased for one tenth that amount.