UNTREATED
HEAR-TREATED

The ring on the right is set with an untreated sapphire from the Mogok region of Myanmar. A blue mosaic pattern appears beautifully within the gemstone. It is a gem-quality sapphire with a gentle yet powerful personality. When viewed from the correct angle, rutile “silk” inclusions that intersect at angles of 60 degrees can be faintly seen inside the gem. These inclusions provide proof that the sapphire is a natural stone that has not been heat-treated. Gemstones are creations of nature, and therefore imperfect. As long as the silk inclusions do not have a decisive effect on beauty, I believe that they should be accepted. Expecting the perfection of synthetic in natural stones is unreasonable, and the time has come to realize that such thinking is what leads to the excessive treatment of natural gemstones.

The sapphire in the ring shown below is heat treated, as are about 90 percent of the sapphires on the market today. It is a gem-quality sapphire from Sri Lanka, with a beautiful mosaic pattern of blue tones. Aquamarine and citrine have long been heat treated at temperatures of approximately 400C (752F) without any problems. However, the heat treatment of sapphire and ruby is done at temperatures of 1,600-1,900C(2,912-3,452F), close to their melting point, and carries with it an inherent threat to the durability of the gemstones. It is amazing that there are many local dealers in Sri Lanka who can tell the difference between untreated and heated stones just by looking at them. Treatment and non-treatment are difficult to distinguish with just the unaided eye, but if stones are separated by source into groups of untreated versus heat-treated and compared, subtle differences in transparency and beauty can clearly be seen.

The history of 20th-century gemology has been one of protecting natural gemstones from synthetic materials. In the 21st century, the challenge will be to enable the judgment of the quality of each type of gemstone, through full disclosure of the various treatments of natural gems, and to maintain an environment in which their proper values can be understood. This will protect gemstones that don’t require treatment from being treated excessively just for the sake of greed.