- Carat is specifically a measure of a diamond's weight, and by itself may not accurately reflect a diamond's size.
- We tend to evaluate diamond size by viewing it from the top because that is how diamonds are presented to us when set into a ring.
- To understand diamond size, carat weight should be considered in conjunction with two other criteria:
- Distance in millimeters across the top of the diamond.
- Diamond's cut grade.
This print out illustrates how diamonds of different carat weights and shapes will appear when viewed from the top down.
Your diamond may differ from the printout in length/width ratio, table, and depth.
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As the name suggests, carat weight specifically refers to a diamond's weight. However, much as a person's weight does not necessarily correlate with height, carat weight, by itself, may not accurately reflect a diamond's size. To gain a precise understanding of diamond size, Blue Nile recommends considering carat weight with two other characteristics: 1) the distance across the top of the diamond measured in millimeters, and 2) the diamond's cut grade.
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.
A diamond's cut grade should also be considered because, as we noted in the cut grade section, when a diamond is cut with the proper proportions, the maximum amount of light (or sparkle) is returned out of the top of the diamond. Thus, when a diamond is well cut, the light reflected out of the top makes it appear larger. In addition, much of the weight of a poorly cut diamond, for example, may be "hidden" in the base of the diamond, making the diamond appear smaller than its carat weight would imply.
It is therefore possible to have a diamond of a lower carat weight, but higher cut grade, that appears larger than a diamond with a larger carat weight, but poor cut.
Once you've selected your cut, colour, and clarity grade, it's easy to determine the carat weight of diamond that will fit within your budget.
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.
This chart illustrates how diamonds of different carat weights look when set in a ring. Note that a 2-carat diamond does not appear to be twice the size of a 1-carat diamond when viewed from the top.