Gemstones
Heat Treatment in Rubies and Sapphires
The great majority of rubies and sapphires on the market are heat-treated to improve colour and clarity, an accepted practice that still must be disclosed.
Why heat is used
Controlled heating can dissolve silk-like inclusions that cause haziness, intensify or even out colour, and improve overall transparency in corundum (the mineral family of ruby and sapphire).
Industry acceptance and disclosure
Heat treatment alone, without added elements, is widely accepted across the trade and does not need to be hidden, but it does need to be disclosed, and it affects value compared with untreated stones of similar visual quality.
Beyond simple heat: diffusion
Some stones undergo beryllium or titanium diffusion treatment during heating, introducing colour-causing elements from outside the stone; this is a more significant treatment that affects value more and requires clear disclosure, ideally with lab confirmation.
Buyer checklist
- ✓ Ask specifically whether a ruby or sapphire is 'heated only' or diffusion-treated
- ✓ Request a lab report for high-value stones to confirm treatment type
- ✓ Expect unheated stones to carry a notable premium when documented
Verification tools & references
Every Riakoob piece arrives certified, insured and covered by our 12-month value promise.
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