Carat

Unit of mass

The carat is a unit of Masse used for the gemmeous . This word comes from the old Greek keratia meaning horns and indicating the Caroubier whose broad beans were used as standard of weight, which then passed by the language Italian ( carato ) and by the Arab ( qîrât , small weight). The measurement of weight kerátion corresponding to the third of the Mite).

In 1907, the carat (metric) was defined by the 4th General conference of the weights and measures (CGPM) as being equal to 200 milligrams. Nowadays the International office of the weights and measures (BIPM) clearly classifies it apart from the international Système of units (IF).

Purity

The carat (symbol ct ) is a measurement of Pureté of metals invaluable such as the Or. In this context, a carat represents 1/24e total mass of a Alliage.

For example, of gold to 15 carats means that in 24 grams of alloy, one has 15 grams of pure gold. Gold 24 carats is pure gold.

Gold having a molar Mass higher than that of the elements with which it is generally allied (money and copper for example), atomic percentage of gold, i.e. the number of atoms of gold percent atoms of alloy, is lower than the mass percentage of gold. Thus, a gold snap ring 18 carats of 10 grams contains 7,5 grams of pure gold, but less 75 % of the constitutive atoms are gold atoms.

Moreover, according to the nature and the relative proportion of the secondary elements, various gold alloys having the same number of carats can present different percentages atomic of gold.

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