Ever wondered how star sapphires get their stars? It's created by an optic feat called asterism, from the Latin astrum meaning star. For a star sapphire to appear, the stone must have spindly, needle-like inclusions of a mineral called rutile that grow and intersect each other within corundum, the mineral we know as sapphire and ruby (yes, star rubies are also possible!)
To cut a perfect star is no easy feat. After determining that a star is even possible, due to a sheen on the rough gemstone, a lapidary must find the gemstone’s optic axis, and then begin to fashion the stone into a rounded cabochon shape. High quality star sapphires are cut to center the stone’s asterism as perfectly as possible in the middle of the cabochon, and keep the points of the star of similar length. The higher the dome of the cabochon, the less the star will ‘move’ under a light source or when rotating the gemstone at different angles.
Snug in a platinum, diamond accented mounting, our Art Deco star sapphire ring was most likely designed for the stone set into it. The underside of the cabochon is rough and uneven to keep the rutile inclusions needed for a lovely, strongly visible star.
And, for a little gemstone bling, take a look at some of the most famous star sapphires, one of which is on display here in New York!:
The Star of India, which lives in New York's American Museum of Natural History, is 563 cts.
The Black Star of Queensland, no longer on public display, is 733 cts.
The Star of Asia, currently housed in the Smithsonian, is 330 cts.