Ruby

Ruby is probably one of the most expensive and valuable colored gemstone, especially when it is not treated in any way. Finest quality stone can cost more than a diamond. It is the red gemstone quality from corundum mineral family (any other color of corundum stones are called sapphire), ruby gives its red color duo to the presence of chromium into the crystal. It is a very hard stone valued with 9 on the Mohs hardness scale.
Find a fine ruby gemstone with good color and nice eye clean clarity is very difficult especially, in larger sizes over 3 carats, when they becomes really expensive. The major sources of this rare material are: Mogok in Myanmar, Thailand, Sri Lanka, Africa, Vietnam, Brazil, Pakistan and other countries. Like emerald, diamond and sapphire, it is one of the precious stone group. This kind of gemstone is commonly treated by heat to enhance color and clarity, sometimes it is also treated by fracture filled and diffusion, a more invasive treatment, to enhance the color and clarity. Ruby when cut into cabochon can presents an interesting optical effect called asterism caused by rutile inclusions, it displays a dancing star (with six or twelve rays) on the surface of the ruby. Read more.