Shimmering colours and verified purity, the name gemstone, is a historical name that applies in France to the four gems that are diamond, sapphire, ruby and emerald. Gems must be natural, of a certain hardness, as well as of a relative beauty, they are thus in general quite rare. Some of the precious stones, because of their exceptional qualities (purity, rarity, quality or even history) are described as jewels. . . 


Precious stones, formerly semi-precious or semi-fine stones, a category that concerns all gems that do not appear in the previous four (garnet, lapis lazuli, cornelian, jasper, etc. ). This category is defined by a list from CIBJO (International Confederation of Jewellery, Jewellery, Goldsmithing of Diamonds, Pearls and Stones) 


Organic stones, a category that includes gems made from organic matter and not mineral (amber, a fossil resin, coral, formed by colonies of polyps, mother-of-pearl, inner lining of some molluscs, pearl, composed of mother-of-pearl used by the mollusc to protect itself from a foreign element, jet, a coal derivative, etc. ).