Diamond Guide - Carat Weight

How Big is a Carat?

A carat is equivalent to 1/142 of an ounce. That means that it would take 142 1 ct. diamonds to weigh an ounce. The carat was derived by ancient Mediterranean people who used the weight of a carob tree seed as a unit of measurement.

One carat is divided into 100 points. So a quarter carat diamond would be a 25 point diamond. Likewise, a .19 ct. diamond would be a 19 point diamond.

Carat Weight And Value

The rarer the gem, the more valuable it is. Larger diamonds are more valuable than smaller ones, because there are less of them. However, the price of a diamond does not go up at the same rate as the weight. For instance, if a 1/2 carat diamond costs $2000, a 1 carat diamond of the same color, clarity, and cut could cost more than $6,000 (more than twice as much).

Cutting For Carats

As a matter of practice, most diamonds are not cut to the ideal proportions. They are not cut to display maximum brilliance. Instead they are cut for maximum weight retention, thus giving consumers the illusion that they are getting more diamond for their money. This is how it works. A rough diamond crystal that is 6mm across will cut a 3/4 ct. diamond if it is cut for maximum beauty. Because of the shape of a typical diamond crystal, the cutter can leave some extra on both the pavilion (bottom) and the crown (top), and end up with a 1ct. diamond. The diamond merchant will then tell the customer that he can sell his 1 ct. diamond for the same price as a 3/4 ct. diamond from Gannaway Bros. You can bet he will not show his bargain priced 1 ct. diamond next to a properly cut diamond, because it will be smaller, having a 6mm diameter rather than the 6.5mm on a properly cut stone. It will also be a lot less brilliant, because of the improper proportions used to produce the additional weight.