Ceylon Star Sapphire — Unheated
ENCYCLOPEDIA · SKYJEMS
Ceylon Star Sapphire — Unheated
- Key concepts
- ceylon star sapphire, star sapphire, asterism, sri lanka star sapphire, unheated star sapphire
A star sapphire carries a six-rayed figure that glides across the dome as the stone moves. The effect is called asterism, and it comes from needle-like rutile inclusions arranged along the crystal's own structure — the same silk that, in a faceted sapphire, would be counted a flaw. In a cabochon it is the entire point.
Sri Lanka has been the classic source for centuries, and its stars tend to run blue, sometimes with a grey or violet cast.
What separates a good star from an ordinary one
Four things, in roughly this order. The star should be straight, complete and centred, with all six legs present rather than fading out. It should be sharp rather than diffuse. The body colour should be a clean blue rather than a muddy grey. And the dome should be cut high enough to gather the star without turning the stone into a marble.
A star that only appears under a single hard light and vanishes in a room is a weak star, whatever the size of the stone.
Treatment — the question to ask
Sapphire is routinely heated, and star sapphire carries its own specific concern: diffusion treatment can be used to create or strengthen an asterism. That is exactly the sort of thing to ask about by name rather than in general. Our Ceylon star sapphires are unheated, and treatment is confirmed stone by stone rather than assumed. Review each listing and its documentation for the individual gem.
Reading the lab report
A report on star sapphire states species = corundum, variety = sapphire, records the phenomenon, and records treatment. GIA is the laboratory we lead with, and where a stone carries a GIA report we list its number on the product page. The wider selection is assessed in-house.
What to look at
(1) is the star complete, centred and straight; (2) is it sharp under ordinary room light, not just a torch; (3) body colour, clean rather than grey; (4) dome proportion; (5) treatment, asked specifically, including diffusion.
Skyjems inventory snapshot
Browse sapphire at /collections/sapphire. Skyjems' selection changes as stones are added or sold; review each current listing for its own documentation.
Private viewings
Contact Skyjems at +1-416-366-3335 or visit Skyjems' private-viewing page.