When evaluating the value of a diamond, its weight plays a major role, especially if the stone is small.
All over the world, the weight of diamonds is measured in carats, abbreviated ct (1 carat = 0.2 grams).
For weighing, jewelers use ultra-precise weights. You can also find out the approximate weight by eye since there is a relationship between the diameter of a diamond and its mass.
For example, diameter 2.0 mm is 0.03 ct, diameter 3.0 mm is 0.10 ct.
Stones weighing up to 0.01 ct are considered chips. This is followed by small (up to 0.29 ct), medium (0.3 - 0.99 ct) and large diamonds (over 1 ct). As a rule, stones over 6 ct are sold at auctions, and giants of 25 ct get their own names.
A diamond is evaluated according to the Tavernier rule. To get the value of a stone, you need to multiply the square of its weight (in ct) by the price of one carat. It turns out that a 2-ct diamond costs three times more than a one-carat diamond, and a 3-ct diamond will overtake it at a price of 10 times.