Cubic Zirconia size chart by Carat Weight May 01 2013

Measuring Cubic Zirconia Loose Stones: CZ size comparison to diamonds

When people refer to the size of a diamond, they’re not actually talking about the size dimensions of the stone.  The size of a diamond is measured in its weight.  The word "carat" comes from the "carob" seed, the original unit of measure for diamond traders.  Carat is the unit of mass for gemstones and is used as a way to compare one stone to another (Note: Carat weight is unrelated to the similar sounding karat, which refers to gold's purity).

Whether you're shopping for finished jewelry set with CZ or loose cubic zirconia stones, it's important to know how these stones are actually measured.

When comparing diamonds and Cubic Zirconia, you first must understand that the weight of a diamond is different from the weight of a CZ because of differences in density.  In fact, Cubic Zirconia are 1.7 times denser than a diamond. Since the carat weight of a gemstone is a function of its weight, the dimensions of a 1 carat real-weight diamond will not be the same as the dimensions of a 1 carat real-weight Cubic Zirconia. If using real-weight measures, a Cubic Zirconia stone that matched the weight of a 1 carat diamond would be smaller, more dense, and heavier. 

So how does a 1 carat diamond compare to a Cubic Zirconia stone?  To account for the weight difference and to make life a little easier, Cubic Zirconia are measured in millimeters which references the same dimensions as a diamond carat equivalent.  We take the dimensions of an absolutely perfect diamond, measure its height and width, and voila – that’s the dimensions we use for an equivalent Cubic Zirconia. For example, a perfect Round Cut one-carat diamond is comparable to a 6.5 mm Round Cut Cubic Zirconia.  In other words, a 1 carat Round Cut Cubic Zirconia diamond equivalent is 6.5 mm. 

When you’re shopping for jewelry on, know that we use carat-equivalent sizes.  That means that when you buy a 2 carat Cubic Zirconia pendant, we match up the size dimensions for a perfect 2 carat diamond and make sure you get a match in size: that would be an 8.00 mm CZ stone, or a two-carat diamond equivalent.  

If you need help figuring out what size your stone is, measure the stone using the instructions below and use our comparison chart to determine the size.

CZ and diamond common stone shapes

CZ size comparison to diamonds


Shop finished CZ jewelry by stone shape

 Asscher Cut

 Cushion Cut 

 Emerald Cut
 Heart Cut  Marquise Cut  Oval Cut
 Pear Cut  Princess Cut  Radiant Cut
 Round Cut  Triangle Cut  Trillion Cut


3d images of loose "diamond" clear cubic zirconia stones

Shop loose Cubic Zirconia stones by shape

 Asscher Cut Cushion Cut Emerald Cut
 Heart Cut  Marquise Cut  Oval Cut
 Pear Cut  Princess Cut  Radiant Cut
 Round Cut  Triangle Cut  Trillion Cut