Midnight Blue Oval Sapphire from Thailand

About Blue Sapphire

Blue sapphire is the blue variety of corundum, a crystalline aluminium oxide. Its colour ranges from pale cornflower blue to deep royal blue and is usually caused by small amounts of iron and titanium. Fine stones are transparent to translucent, although colour zoning and inclusions are common. Some sapphires show pleochroism, displaying slightly different blue tones when viewed from different directions. Needle-like rutile…