Ceylon Blue Sapphire thermal enhancement: microscope indicators of low-temp heating?

Traditional Beruwala and Ratnapura brokers refer to untreated stones as "kaduwa"; insist that the memo explicitly certifies "No indications of thermal enhancement" rather than ambiguous phrasing.

Always record high-resolution inclusion maps on camera before handing any stone over for independent re-cutting or testing to prevent substitution swaps.

Verify the cert issuer: several independent private labs in Colombo issue certificates with lenient heating disclosures. Only recognized government or accredited international labs carry weight during resale.

Sri Lanka’s alluvial gem gravels (illam) produce uniquely unaltered hexagonal crystal geometries; stones showing fire-skin surfaces on the rough edges reveal heat treatment immediately.

Short-wave UV luminescence lamps often reveal chalky greenish-blue fluorescence in low-heated stones where iron-titanium pairs have been artificially mobilized.

Never examine sapphires under fluorescent market shop lights; standard daylight bulbs with high CRI values reveal true blue saturation without deceptive violet flares.