In the gem trade, “カラット” is often used as the unit of quality. The term carat, originally in Greek, means the seed of a kind of “carob tree” that grows on the Mediterranean coast of Europe. The ancients believed that the quality of each seed was the same, so it was used as a weight for weighing gems, and the quality of gems was also expressed in several carats. It is also said that more than 3000 数年前, people found the first diamond in India. There was a carob tree there. The beans on the tree weighed 0.2g. People used the quality of one bean as the quality of the diamond.
実際には, the seeds of carob are not the same weight. 近年では, some people in our country have collected hundreds of these seeds. After weighing them with a precision balance, they know that their actual mass is 143-240mg, which shows the big difference. 今日, when the measurement method is becoming more sophisticated, countries have set a standard quality for carats. 初めに, it was not uniform. In some countries, 210 mg was 1 CT, while in other countries, 180 mg was 1 CT. で 1877, 英国, フランス, and the Netherlands, the major gem trading countries at the time, agreed that 205mg was 1ct. で 1907, in order to facilitate conversion to the metric system, the world unified regulations:
1ct = 200mg = 0.2g
This is called “Metric Carat”.
Since diamonds are very precious, diamonds as small as 0.01ct are also useful. In order to easily explain the quality of small diamonds, foreign countries use “Point”, the quality of which is:
1ct = 100Point
Point is translated as “分” according to Chinese custom, つまり, 1ct = 100 ポイント. It is very convenient to use points to express the quality of small diamonds. 例えば, a small diamond weighing 0.01ct can be called a 1-point diamond, a small diamond weighing 0.04ct is called a 4-point diamond, and a 20-point diamond is a diamond weighing 0.2g.