Carats and troy weight

The purity of gold is measured in terms of carats (spelt karats within the US). A carat is one twenty-fourth a part of the full of the metal object. An object that's twenty four carat gold contains twenty four elements gold or is pure gold. The word carat comes from either the carob or coral tree seeds that were used to live the load of precious gems. In medieval times gold’s purity was measured against a coin referred to as a mark, that weighed twenty four carats. as a result of gold was too soft to be used to form marks, it absolutely was mixed with different metals. The proportion of different metals was measured by what percentage of the twenty four carats they weighed in proportion to the gold. Gold is additionally typically weighed in terms of troy weight. Troy weight was once used to live grain however since medieval times has been used for precious metals. The name is alleged to derive from the French city of Troyes, a serious medieval centre of commerce.