:: SUWA/Dictionary-Untreated Gemstones::

Weight : 4.31ct
Size(mm) : L9.2 x W7.9 x D6.20
Sri Lanka, Untreated
Gem Quality

Traditionally, the most favored color for sapphire is the rich and soft "cornflower blue" seen in Kashmir stones. Though there is virtually no mining in Kashmir now, sapphires that approach this color are found in Sri Lanka. Some of the sapphires that are mined in Sri Lanka (and recently in Madagascar) are not heated. These are transparent with a somewhat velvety appearance, giving them a unique character. Similarly, there are sapphires from Myanmar and Kashmir that are not heat-treated.

There are subtle differences between the liveliness of a naturally beautiful color and that brought about through heat treatment. An individual's preference is a personal decision, but one that should be made with the knowledge of whether the beauty is natural or a result of treatment.
SUWA is particularly careful to choose sapphires that nature has already blessed with a "natural beauty."

Map of Major Sources

Untreated Sapphire

Untreated and heated sapphire

Lapidaries in Sri Lanka who deal in sapphires can determine whether a stone is untreated or heat-treated by looking at the finished stone's appearance. Differences in the transparency and color result in differences in beauty. Simply speaking, sapphire gets its blue color from the elements titanium and iron. If these elements are present in a pale or colorless stone, heat treatment causes a chemical reaction that brings out a deeper blue color.

	Silk Inclusions Corundum may contain fine, needle like crystal inclusions of rutlie (titanium oxide). These are commonly called "silk" because of their thread like appearance. Silk inclusions can be seen in about 30% of the untreated sapphires from Sri Lanka. They often melt during heat treatment, so the presence of silk suggests that a stone has not been treated.
	Characteristics of Heated Sapphire The temperatures used during the heat treatment of corundum are often high enough to melt or otherwise seriously damage inclusions of other materials such as rutlie, apadte, or hematite. Melted crystals like these "snowball" inclusions are often seen in heat-treated sapphires and rubies.

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