𝐓𝐇𝐄 𝐏𝐑𝐄𝐂𝐈𝐎𝐔𝐒 𝐆𝐄𝐌𝐒𝐓𝐎𝐍𝐄 𝐒𝐀𝐏𝐏𝐇𝐈𝐑𝐄
Chemical Formula Al2O3
Color White, Colorless, Blue, Green, Yellow, Orange, Brown, Pink, Purple, Gray, Black, Multicolored
Hardness 9
Crystal System Hexagonal
Refractive Index 1.76 - 1.77
SG 3.9 - 4.1
Transparency Transparent to opaque
Double Refraction .0008
Luster Vitreous to adamantine
Cleavage None, but may exhibit parting
Mineral Class Corundum



The most valuable color of Sapphire is a cornflower blue color, known as Kashmir Sapphire or Cornflower Blue Sapphire. Another extremely valuable Sapphire form is the very rare, orange-pink Padparadschah. An exotic type of sapphire, known as Color Changing Sapphire, displays a different color depending on its lighting. In natural light, Color Changing Sapphire is blue, but in artificial light, it is violet. (This effect is the same phenomenon well-known in the gemstone Alexandrite). Yellow and pink Sapphire have recently become very popular, and are now often seen in jewelry.

Going way back in time, Sapphires (excluding blue) were often called the same name as a popular gemstone of that color with the prefix "oriental" added to it. For example, green Sapphire was called "Oriental Emerald". The practice of applying the name of a different gemstone to identify the sapphire was misleading, and these names are no longer used. What was once called "Oriental Emerald" is now called "Green Sapphire". The same holds true for all other color varieties of Sapphire. However, the word "Sapphire" in its plain context refers only to blue Sapphire, unless a prefix color is specified. Sapphire with a color other than blue is often called a "fancy" in the gem trade.

Sapphire often contains minor inclusions of tiny slender Rutile needles. When present, these inclusions decrease the transparency of a stone and are known as silk. When in dense, parallel groupings, these inclusions can actually enhance by allowing polished Sapphires to exhibit asterism. Sapphire gems displaying asterism are known as "Star Sapphire", and these can be highly prized. Star Sapphire exists in six ray stars, though twelve ray stars are also known.

Sapphire is pleochroic, displaying a lighter and more intense color when viewed at different angles. Some pleochroic Sapphire is blue when viewed at one angle, and purple at a different angle. Color zoning, which forms from growth layers that build up during the formation of the stone, may also be present in certain Sapphires. Color zoning is responsible for certain Sapphires having lighter and darker colors in different parts of a crystal. Some Sapphire gemstones may even be multicolored such as purple and blue.

Sapphire is a tough and durable gem, and the only natural gemstone harder than Sapphire is Diamond. Despite this, Sapphire is still subject to chipping and fracture if handled roughly, and care should be taken to ensure it is properly handled. Sapphire was first synthesized in 1902. The process of creating synthetic Sapphire is known as the Verneuil process. Only experts can distinguish between natural and synthetic Sapphire.