Gemstone Treatments & Disclosure

Most sapphire on the market has been heated, and that's not a defect. But unheated stones command a real premium, and the reasons why come down to rarity, permanence, and what a certificate can (and can't) prove. Here's how to think about the price gap.

Gemstone treatment means any process that changes a stone's colour, clarity, or durability. Here's what each of the 19 recognised treatment types means, how to spot a treated stone, and how treatment affects value.