SEPTEMBER BIRTHSTONES – SAPPHIRE The name “sapphire” can also apply to any corundum that’s not ruby red, another corundum variety. Besides blue sapphire and ruby, the corundum family also includes so-called “fancy sapphires.” They come in violet, green, yellow, orange, pink, purple, and intermediate hues. Some stones exhibit the phenomenon known as color change, most often going from blue in daylight or fluorescent lighting to purple under incandescent light. Sapphires can even be gray, black, or brown.
Mineral: Corundum;
Chemistry: Al2O3;
Color: Every color but red;
Refractive index: 1.762 to 1.770;
Birefringence: 0.008 to 0.010;
Specific gravity: 4.00;
Mohs harness: 9;
COLOR: Sapphires come in a variety of colors. Preferred sapphires have strong to vivid color saturation, regardless of hue;
CLARITY: Blue sapphires typically have some inclusions, but they generally have better clarity than rubies;
CUT: Sapphire is often cut with a brilliant pattern on the crown and a step cut pattern on the pavilion;
CARAT WEIGHT: Blue sapphires range in size, and large blue sapphires are more readily available than large rubies~
28 March 2019
