September Birthstone - Sapphire Roger K. Pabian Sapphire crystals, Sri Lanka. If you were born in the month of September, sapphire is your birthstone. The axes are arranged in a hexagonal crystal, a crystal with four axes, three of which are of equal length and intersect at 60 degree angles, and one of which is unequal in length to the others and intersects the others at a right angle. Sapphire's companion variety of corundum is ruby.
Rubies are red to orange-red to purplish red.
If corundum is pink, the United States Federal Trade Commission requires that the stone be sold as a sapphire. In the simplest terms, corundum that is any color other than red is a sapphire. Except for color, all of the other physical and optical properties of sapphire are identical to those of ruby and you are referred to the ruby page for these data. Supply and demand has dictated that cornflower blue sapphires are the most expensive. These stones are rare and the finest examples come from Kashmir, a mountainous area in northern India on the Pakistan border.