2.5ct Sapphire Inside-Out Hoop Earrings, Sterling Silver, 1 Inch Sapphire, a member of the corundum family of gemstones, is blue in color, from cornflower blue Ceylon sapphires,to dark blue Australian sapphires, to right royal blue Burmese sapphires. Most common treatment for the enhancement of color is heat treating. In the heat treating process, rough un-cut sapphires are heated to 1700-1800 degrees Celsius, which improves both color and clarity. All sapphires that SuperJeweler sells are heat treated for the enhancement of blue color and clarity.