https://www.gia.edu/gems-gemology/winter-2018-gemnews-microscopic-observations-blue-sapphires-treated-heat-pressure
Microscopic Observations of Blue Sapphires Treated with Heat and Pressure | Gems & Gemology
A previously unreported microscopic feature could be a useful indicator for corundum treated with heat and pressure.
blue sapphires
https://www.gia.edu/gia-news-research-nr62609
Beryllium Treated Blue Sapphires: Continuing Market Observations and Update Including the Emergence...
An update on the market presence of beryllium-treated blue sapphires and their identifying characteristics. Two large samples (22 and 53 ct) are also described.
blue sapphires