A carat is the weighing scale or unit of weight of a diamond. The word "carat" has its roots in Greek. Back then, carob seeds were considered to have consistency in their mass. Hence, it became a comparative measure of easing out the trade of diamonds. Carat has remained a relative measure for diamonds for a long time. Its net weight was different from place to place until 1907, when it was defined and standardized.

Carat is the weighing scale or unit of weight of a diamond. The word carat has its roots in Greek. Back then, carob seeds were considered to have consistency in their mass. Hence it became a comparative measure easing out the trade of diamonds. Carat has remained a comparative or a relative measure for diamonds for a long time. A carat's net weight was different from place to place until 1907, when it was defined and standardized.

Today, one carat equals 0.2 grams, i.e., the size of a paperclip. A carat is divided into one hundred points. When shopping for a diamond, the most common term you will hear from jewelers is carat, which is how diamonds are presented, coupled with many other features or shapes.

Many diamond sets or rings will have more than one diamond. Therefore, the cumulative weight of all diamonds would be displayed in the description of that item. In that case, you will see the total carat weight (TCW/TW), which is the total weight of all the diamonds in that jewelry. Since every carat is divided into one hundred points, you will find diamonds in different ranges, e.g., 1.25 carats or 0.25 carats. Imagine a dollar in your mind – 1.25 carats would be like one dollar plus a quarter, or 0.25 carats would be like a quarter of a dollar.

The larger the carat weight of a diamond, the higher its price per carat. Two engagement rings, each having a diamond weighing one carat, may cost $2,000, whereas one with a 2-carat diamond may cost $10,000. A bigger diamond can be considerably more expensive than a smaller one. For example, a Round SI1 F V.Good Cut 1ct will cost $4,800, while a similar 2ct will cost $15,000 (the per carat weight of the latter becomes $7500). At the same time, many other factors determine the price of a diamond, including color, clarity, and cut.

The carat weight of a diamond can be determined by measuring—table up—the diamond in millimeters across the widest and narrowest points, apart from the depth or height. Once these measurements are taken, they can be put into any online diamond carat weight calculator. Afterward, you will be required to specify the shape of your diamond, following which you will be able to see its exact weight in carats.