The carat weight
The carat is a unit of weight. It originates from the orient, where, in ancient times people used carob seeds to weigh precious stones.
The marquise or navette diamond was once very fashionable.
Diamonds are a raw material, everything that cuts or abrades is diamond-based. They are also used in science for research into diamond lasers and diamond forges.
Demand has grown so much that these days synthetic diamonds are used. In 1955, General Electric invented the first synthetic diamonds.
Charles VII, in 1430, was one of the first to give a wedding ring to Agnès de Sorel, with whom he was smitten. From the 20th century De Beers have had a quite powerful marketing campaign, i.e. the democratisation of diamonds as a symbol of love and I believe many of you ladies are wearing them tonight.