Top 10 Varieties Of the Gemstone SapphireSapphire can occur in almost all colors except red.
Sapphire hardness on Mohs scale is 9 /10 (one of the best ever, 3rd hardest gem after diamond and moissanite).
The Top Ten
Star Sapphires have rutile needles inside responsible for the amazing optical effect called asterism (star-like effect). - Metal_Treasure
It's a pink-orange sapphire, which is the rarest color of sapphire. Most jewelers never seen one. - Metal_Treasure
Sapphires that exhibit two or more colors within a single stone (mostly found in Australia) - Metal_Treasure
It's Colorless Sapphire - can be used as a diamond alternative - Metal_Treasure