star sapphire

a sapphire, cut cabochon, exhibiting asterism in the form of a colorless six-rayed star.

Origin of star sapphire

First recorded in 1795–1805

Was I making game of you when you discovered me looking out of your star-sapphire yesterday?

Lilith |George MacDonald
The typical asteria is the star-sapphire, generally a bluish-grey corundum, milky or opalescent, with a star of six rays.

Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 7 |Various
Perhaps your hands would look wrong with a ring, unless I could find a star-sapphire set in silver.

Sinister Street, vol. 1 |Compton Mackenzie
Like the inside of a pearl; like the inside of a star-sapphire; like a rainbow at twilight.

A Northern Countryside |Rosalind Richards

At other times the star-sapphire which Burton carried on his person proved a valuable auxiliary—and convinced where words failed.

The Life of Sir Richard Burton |Thomas Wright

star sapphire

a sapphire showing a starlike figure in reflected light because of its crystalline structure