Rubies are bright red precious stones which can be anywhere from transparent to opaque. They are the red version of corundum. According to Minerals.net, rubies get a nine on the hardness scale.
Rubies can range in color from a bright red to a rich, reddish brown. A deep red stone with a bluish tint, called the Pigeon's Blood Ruby, is a highly desired type of ruby among jewelry enthusiasts. Rubies are used in various types of jewelry, including necklaces and earrings. Large ruby gems are very rare and can cost a few thousand dollars a carat, according to Minerals.net. The ruby is a durable gem, but it still should be handled gently to prevent fractures and chipping.