Carat WeightThe term for how much a diamond weighs (or the total of diamond weight in a 3 stone diamond ring) is "Carat."

One carat weight equals 200 milligrams.

The carat weight may also be expressed in points.

One carat equals to 100 points.

Remember, Carat refers to the weight and not the size of a diamond.

A shallow cut diamond may have a larger diameter and look bigger than a deep cut diamond of the same weight.

The person selling a diamond will specify the exact carat wieght to the nearest hundredth of a caret, in decimal format.

So, a 1-carat diamond has 100 points, while a 3/4-carat diamond has 75 points.  See how that works?

Most retailers follow the fraction designation.

However, now if you come across one using the point system, you know how to interpret it.

One thing to keep in mind, is that how a diamond is cut may actually skew the appearance of its weight.

For example, a diamond that is very wide may have a shallow depth and therefore is actually a smaller carat weight than a diamond that appears rather narrow, but is set deeply.

Also, as we've seen from our other pages on the 4 c's of diamonds, there is much more that goes in to the value of a diamond other than its carat weight. 

In fact, the carat weight is the last of the four components in determining its value.

Another helpful example of this is to consider that an exceptionally ideal cut diamond can sell for very close to $20,000 per carat, but a much lower quality cut will sell for closer to $1,000 per carat.f

Lastly, an interesting piece of information should you be one of those lucky ones who can afford such a prize;

The value of a diamond will also increase quite disproportionately to the size of the stone.

What this means is that, since larger diamonds are very rare, given all other aspects being equal, the 3 carat diamond will be much more expensive than 3x the price of a 1 carat diamond.