Sapphire is the official September birthstone. It is just one of the birthstones and semi-precious stones that are assigned for several Zodiac signs which include Taurus, Pisces, Sagittarius and Virgo. Sapphire is also the gem that could be given for a 5th, 23rd as well as a 45th wedding anniversary and for a 65th wedding anniversary, a star sapphire should be given.

It is the second hardest of the natural minerals, with a hardness of 9 on the Mohs scale. Although blue is the most common color for sapphires, they could come in nearly any color, which includes yellow, white, green, colorless, orange, pink, brown, and purple. A variety of this semi-precious stone which is even more valuable than blue sapphires would be the rare orange-pink variety.

Those sapphires that have inclusions of numerous tiny and rutile needles show a kind of optical property which is called asterism. This would be the star-shaped effect that is seen in star sapphires. It is also usually just seen in cabochon cuts. These star sapphires typically have six ray stars, however there are those that have twelve rays. Sapphires could also have a cat’s eye effect when they are cut en cabochon. When this effect is displayed, there would be a single thin band of light than goes down the stone’s center. This effect is known as chatoyancy.

There is also a very rare variety of sapphire, which is known as the color changing sapphire. This could exhibit various colors when under different kinds of light. It is blue under natural light and then violet under artificial light. This effect could also be seen in alexandrite.