The Four Cs of a Diamond: Diamond Carat

The unique unit of weight measurement used to weigh gems and diamonds is referred to as carat. People often confuse carat weight with visual size, but depending on the shape and type of stone being weighed, carat weight will show itself differently. For example, a 1 carat round diamond will measure larger than a 1 carat round sapphire due to the difference in density between the two stones. The phrase total carat weight (t.c.w.) is used to describe the total weight of all diamonds and gemstones in a piece of jewelry.

Carat and Price Because larger diamonds are found more rarely in nature, they are more expensive. For example, a 1 carat diamond of a given quality will always be considered more valuable than two .5 carat diamonds of the same quality. As a general rule of thumb, a diamond of double the weight costs around four times as much.

If you want to get more bang for your buck, you might choose to go with a diamond that is an “under size,” meaning just below one of the cutoff weights. The cutoff weights, or magic numbers in the industry, are .50 ct, .75 ct, .90 ct, 1.0 ct, 1.5 ct and 2.0 ct.