Corundum is the second hardest precious stone after diamond. There are corundums with asterism effects. In jewelry world, transparent corundums with intense colors traditionally have their own names. Red corundum is known as ruby, blue - as sapphire.
The term "corundum" is probably derived from a Sanskrit word “kurivinda”, which was used for the name of ruby. Traders and jewelers often used the word "oriental" in the names of different sorts of corundum to highlight the quality of those stones. Nowadays, the production of synthetic corundum is at industrial scale.
In many countries red corundums have been considered as symbols of passion and sensual love. They are esteemed as the stones helping concentrate the sexual energy. On the contrary, light blue and dark blue corundums are able to tame passion.
Red corundum is believed to have positive influence over the treatment of the nervous system’s diseases, the circulatory system, the spine and joints. Corundums with that color help to combat sleep disorders. Light blue and dark blue corundums would assist to reduce blood pressure and to deal with insomnia. It is believed that such corundums are useful in the treatment of eyesight diseases. According to crystal therapists, blue corundum can relieve back pain caused by osteochondrosis.