All precious stones are rare. This is the reason they are so valuable. If diamonds to make replica van cleef & arpels ring were as common as coal they would be as cheap. But some stones are rarer than others. A stone may be rare in color, as the red diamong; or rare in size, as large emeralds.

This quality of a stone is the only one of the three essentials which is relative, as it varies with new discoveries of gem deposits. The crocidolite is an example of this. Years ago it was used in fine jewelry and sold by the carat. Today it is so plentiful that it is used only for cameos and intaglios.

The other two essentials, beauty and durability, are constant, as they depend upon the chemical and physical composition and structure of the stone. The replica van cleef & arpels jewelry with diamond is generally regarded as the prince of gems. In composition the diamond is the same substance as coal, lampblack, and graphite; that is, pure carbon but in its crystalline form.

In color the diamond may be perfectly transparent or in shades of yellow, brown, green, gray, red, blue, or black. For example, the famous Florentine diamond is light yellow,the Tiffany deep orange, the Hope diamond blue, one owned by the Czar of Russia a brilliant red, and a pear-shaped one in the Dresden vaults a bright green. The blue-white diamonds having a distinct bluish tint, are the finest, the white, colorless diamonds are next, and those with a yellowish cast, or "off color" stones, least valuable.

Diamonds are usually reansparent,though the gray or black fake van cleef & arpels necklace diamonds known as bort or carbonado are opaque.