Gemstones that are beautiful and that have few defects do not require treatment. Rubies, sapphires, and emeralds polished from crystals that are beautiful to begin with, requiring no heating or fracture-filling, are valuable and rare chance occurrences in nature, each with its own beauty. Imperfections are acceptable as long as they do not greatly affect a gemstone’s beauty. If a certain degree of imperfection is permitted- aside from defects that might result in breakage- more gemstones can be enjoyed in their untreated state as gifts from nature.
On the other hand, bringing out the beauty of gemstones through treatment is not necessarily a bad thing. Increasing the supply of gemstones puts them into the hands of more people. As a result, the cost of high-quality goods comes down, and we benefit from the market expansion that is brought about, However, untreated and treated materials need to be clearly distinguished and fully disclosed in order to maintain the condition of the gemstone industry, because the large difference in the supply of these materials translates into a difference in their values.
The gem dealers of Sri Lanka and Thailand are aware of how rough material from different sources will react to treatment. They know which rubies should be heated at 800-133C
(1,470-2,370F) to remove a bluish hue and make their red more beautiful, which require more severe heating, and which crystals might fracture during treatment. As the temperature used during heat treatment increases, there is also a greater chance that it will affect the gem’s durability.
Treatment has greatly increased the supply of beautiful gemstones. However, we need to beware that for each untreated ruby there are a hundred or even a thousand treated rubies that look the same, giving rise to large differences in their values. Gemstones impregnated with oil require further caution, because in addition to differences in value, their appearance can change over time as the filling material deteriorates. Then there are materials that have totally artificially induced beauty and virtually no value as gemstones, such as irradiation-treated blue topaz, or diffusion-treated sapphires, in which color is artificially added to the surface of colorless sapphires. These are the very reasons why clear disclosure of treatments, including details of the methods, is a must.