Ruby

=Ruby=

by Sergio H. and Owen N.
====A ruby is a pink to red colored gemstone. Rubies are also a var iety of the mineral corundum. The presence of mineral chromium is the cause for the rubies' red color. Rubies are considered to be one of four precious stones, the others being emerald, sapphire and diamond. Price of rubies are generally based on color. The brighter red, the more expensive a ruby is. Cost is also affected by clarity and weight. ruby is also the traditional birthstone of July. The most expensive ruby in the world is called the Sunrise Ruby. ====

Rubies have a hardness of 9.0 on the Moh's scale of mineral hardness. The only natu ral gems that are harder are moissanite and diamond which both have about 10.0 on the Moh's scale.