Most gemstones are minerals that occur naturally in the earth. The most common is quartz, which is made of silicon and oxygen, two of the most common substances found on our precious planet. Even though most people don’t find such crystals unless specifically looking for them, there are still relatively common in the gem world.
One quality that determines the value of a gem is how rare it is. A diamond, believe it or not, is actually the more common gemstone. However, the sales and distribution of diamonds are tightly controlled, which keeps the demand for diamonds of any characteristic in high value. Certainly perfect, flawless diamonds are truly rare, but diamonds themselves aren not particularly rare.
Other gemstones such as sapphires and rubies which are part of the beryl family of minerals are much more rare than diamonds. Rubies are rarer than sapphires and top quality colors in both are extremely rare.
A mineral called benitoite (pronounced bu-ne-tu-it) is found only in the San Benito valley in California, where only a few hundred carats of it are found each year. It is the state gem of California and is a hexagonal-shaped crystal. It can be cut and polished to produce sapphire-colored gemstone jewelry.
Some gems are even rarer than benitoite. They’re so rare, that only three or four of them exist in the world. And the location where the gemstone was found can make a big difference as well. While peridot is a fairly common gem, there were actually several carats of peridot discovered in a meteorite, making that one of the rarest gems ever!