star ruby

synthetic gem

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July 14, 2026

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A star ruby is a variety of ruby that exhibits asterism, a star-like optical phenomenon. This effect is caused by the presence of tiny, regularly arranged mineral inclusions, typically rutile, within the gemstone.12

Synthetic star rubies are produced using the Verneuil process, where purified alumina mixed with chromium oxide (for red color) and titanium oxide (for asterism) is melted and reformed into a boule. After cooling, the boule is heat-treated to create the needle-like rutile crystals that produce the star effect. These synthetic star rubies often display sharper and more distinct stars than their natural counterparts.342

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Verneuil process
Synthetic corundum.
Star rubies and sapphires, first developed in 1947 in the United States, are made by adding one percent rutile (titanium oxide, TiO₂) to the starting powder, forming the boules in the usual manner, and then heat treating them at temperatures between 1,100° C and 1,500°…
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Star rubies and sapphires, first developed in 1947 in the United States, are made by adding one percent rutile (titanium oxide, TiO₂) to the starting powder, forming the boules in the usual manner, and then heat treating them at temperatures between 1,100° C and 1,500°…
Read More