What does heat treatment mean?
Heat treatment is a controlled process used with some natural sapphires to alter or improve colour, clarity, or both. A heated sapphire remains a natural corundum gemstone, but the treatment should be disclosed clearly.
What does unheated mean?
An unheated sapphire has no detected evidence of heat treatment. This conclusion should be supported by a qualified independent gemmological laboratory when treatment status is important to the purchase.
Important: Visual appearance alone is not a reliable way to confirm treatment. Review the laboratory report and make sure its identity, weight, measurements and report number correspond to the gemstone.
Which should you choose?
Choose according to colour, cut, transparency, documentation, budget and intended use. A well-disclosed heated sapphire can be a suitable choice for jewellery. An unheated sapphire may interest buyers who place greater importance on an untreated history. Neither label replaces a complete assessment of the individual stone.
Questions to ask before buying
- Is the stone natural or laboratory-grown?
- Does the report state indications of heating or no indications of heating?
- Does the report match the gemstone measurements and weight?
- Are any additional treatments disclosed?
- Is the certificate included with the purchase?
Available sapphires
Need help reviewing a sapphire?
Contact Ceylon Sapphire with the product link or SKU and any certificate questions.
Further reading: Gemological Institute of America, research on heat treatment of corundum and sapphire.