CARAT WEIGHT

Diamonds are sold by the carat (shown as ct.), which is actually a unit of weight, though most think of a carat in terms of size. Carat by itself may not accurately reflect a diamond's size as viewed from the top. To understand a diamonds size (also referred to as the spread of the stone), carat weight should be considered with 2 more parameters, which are: diamonds measurements and Cut grade.

1.    Diamonds Measurements

When viewing diamonds, check the certificate for measurements listed for each diamond to understand its size. The length and width will tell you exactly how large the diamond will appear when viewed from above. It is important to measure the distance across the top of the diamond as this is how we view a stone when set into a ring.

2.    Diamonds Cut Grade

Two diamonds of the same shape and carat weight may still appear different in size based on the cut proportions. A deeply cut diamond has a greater proportion of its total weight "hidden" in the depth, resulting in a smaller diameter than a well cut diamond.

Two 1 ct. diamonds: The diamond on the left

has a deep cut and appears smaller from above.

Carat weight Or Size is one of the most important determinants of price in diamonds. The value of a diamond increases exponentially with size.

Two diamonds of equal carat weight can have very different value based on other factors (such as cut, color, and clarity). Differences in cut, color and clarity can make a small diamond much more valuable than a large one.

A Carat is equal to exactly 0.2 grams (about the weight of a paper clip). Carat weight is not related to the similar sounding karat, which refers to gold's purity. Much as there are 100 pennies in a dollar, a one-carat diamond is comprised of 100 points. Hence, 50 points is equal to 1/2-carat, and so on.

Size comparison for different shapes

Two diamonds of equal carat weight may also appear very different in size based on the shape of the diamond. For instance, a 1 carat marquise tends to appear larger than a 1 carat round. The chart below illustrates why.

To see the actual size of each diamond shape at various carat weights, see the diamond carat size chart below:

Size Chart-IDIAM click here to download

Buying Tip

Diamond prices jump at the full- and half-carat weights. Diamonds just below these weights cost significantly less. These diamond just short of the full size are called premium weights. For example 0.90 carat diamond will typically cost less on a price per carat basis than a full 1.00 carat diamond. Visually they are difficult to distinguish.