Diamond

The name diamond refer to its hardness (Greek-adamas, the unconquerable). There is nothing comparable to it in hardness . Its cutting resistance is 140 times greater than that of ruby and sapphire, the gemstones next in hardness after diamond. However, the hardness of a diamond is different in the individual crystal direction . This allows one to cut diamond with diamond and/or with diamond powder. Because of the perfect cleavage, care must be taken not to accidentally bang against an edge of a diamond, and also when setting it. Its very strong luster sometime enables the experienced eye to differentiate between a diamond and its imitations. Diamond is generally insensitive to chemical reactions. High temperatures , on the other hand, can induce etchings on the facets. Therefore, special care must be taken during soldering.
In the last fifty years, it has been recognized that there are various types of diamonds with different characteristics. Science differentiates between type la, Ib, Ila, and IIb. This is of little importance to the trade, but does assist the cutter. Due to the optical effects, the high hardness, and its rarity, the diamond is considered the king of gemstones. It has been used for adornment since ancient times.