Catherine Bell (I) Catherine was born in London, but moved to California with her Iranian mother at age 2. Her mother still acts as her personal assistant. As a child, she acted in various TV adverts. She went to UCLA to study biology, but dropped out to become a model in Japan.
When gemstones are identified by category, the following categories may apply: 1  Diamonds â considered the most precious stone in the world. 2  Corundum â contains gemstones like sapphires and rubies. 3  Chrysoberyl â alexandrite and catâs eyes are two common stones of this type.here are other ways to evaluate types of gemstones. People may classify them by hardness on the Mohs scale, by color, by rarity, or by popularity. What is really most important in considering different types is how they appeal and how well they will hold up when used in certain ways.
Of all the precious stones, diamond is the most subject to myth. It is interesting that the myths are of modern rather than ancient origin. Historically, colored gemstones such as ruby and sapphire were more highly valued than diamond, mainly because diamond was not particularly rare.hese days a number of rare semi-precious stones such as alexandrite, demantoid garnet, tsavorite garnet and tanzanite can be just as expensive as ruby and sapphire. Very fine tourmaline, spinel and large aquamarine gems also command very high prices.