Blue sapphire is the most prized variety of corundum, famous for its shades of blue ranging from light blue to intense royal blue. It is one of the four precious stones along with diamond, ruby and emerald.
9硬度（满分 10）
Corundum矿物家族
Heat TreatmentHeat treatment is applied to approximately 95% of sapphires. It permanently improves color and clarity. This treatment is widely accepted in the market and must be disclosed. Heated sapphires are worth 30-50% less than untreated ones of equivalent quality.
Untreated (Natural)Untreated blue sapphires represent about 5% of the market and are highly sought after. They command prices 1.5 to 3 times higher than heated stones. A laboratory certificate (GIA, GRS, SSEF, Gübelin) is essential to attest the absence of treatment.
Beryllium DiffusionTreatment that modifies color on the surface or in depth by beryllium diffusion. This treatment significantly affects value (reduction of 80-95%) and must be disclosed. Diffused stones sell at very low prices (3-50 EUR/ct).
