Gemstone treatments and why disclosure matters

Heating is the most common: it can deepen a ruby's red or turn greenish beryl into blue aquamarine. Fracture filling with glass or resin hides cracks. Some stones are irradiated or coated.

An untreated stone of the same colour and clarity is rarer and usually worth much more. Some treatments, like filling, also make a stone more fragile.

Gemmologists look for tell-tale signs under magnification. For valuable stones, independent laboratories use spectroscopy and other instruments and state the findings on their report.

We disclose every known treatment in writing, and send significant stones for a laboratory report.