Our visual carat calculation helps translate the surface area of a diamond into a carat size equivalent, showing you how large the diamond will appear based on its specific dimensions. This calculation is specific to the diamond shape you’re looking at. You may be able to unlock additional value by finding a diamond that appears larger than its actual carat weight, but cut quality begins to deteriorate at a certain point as the diamond is cut to maximize surface area over sparkle.

StoneAlgo recommends a Cut Score of 7.5 or higher

Cut Score uses every measurement provided by the GIA to calculate a more precise value for the cut grade of Round diamonds. Cut Score is an internal calculation that you’ll only find on StoneAlgo. We noticed a huge disparity between the best and worst GIA Excellent cut diamonds so we created this mathematical model to give you a better idea of just how well cut a Round diamond is based on all of the specs on its GIA certificate (table %, depth %, pavilion angle, crown angle, etc.).

Length-to-width ratio is calculated by dividing the widest part of the diamond by the narrowest part. A length-to-width ratio of 1.00 would be a perfect circle or square. As the ratio rises above 1 the diamond will begin to look more oval or rectangular. For round diamonds you should shoot for a ratio as close to 1.00 as possible and for fancy shapes it really boils down to a matter of preference.

Need help setting your budget? Check out our diamond price calculator to explore diamond prices.

The weight of your diamond and the most common measure to describe diamond size. Our Visual Carat Weight measurement is an even more accurate measure of how large the diamond will actually look based on its surface area, described in terms of carat weight.

The GIA grades diamonds on a scale of D (colorless) through Z (light color). StoneAlgo only shows colorless (D - F), near colorless (G - J), and K color diamonds (faint colored). The most common color grade for diamond engagement rings is H color.

Clarity grades measure the type, size, and location of inclusions on the surface or within the diamond. The most common clarity grades for engagement rings are VS2 and SI1.

1 in 3 diamonds exhibits some degree of fluorescence when exposed to UV light. Some fluorescence can actually be a good thing if you’re shopping for a near colorless (G - J) or faint colored (K) diamond.

After diamonds are cut into their final form, they are polished to be as sparkly as possible. Most people choose very good polish or better.

Sometimes diamonds are cut in a way that is not symmetrical, and this can prevent the diamond from sparkling at its best. We recommend excellent symmetry.

The ratio is calculated by dividing the diamond’s length by its width. For round cut diamonds the ideal L/W ratio is 1.00 - 1.05 while for some fancy shapes it is more a matter of style and preference.

The diamond’s height as a percentage of it’s width.

The width of the table (the flat top of the diamond) as a percentage of the diamond’s full width.

StoneAlgo’s proprietary measure of cut quality for round diamonds. A perfectly cut round diamond will exhibit a noticeable pattern of dark arrows pointing out from the center. Filter by 9.0 - 10 cut score to see what these diamonds look like.

This is the rating for diamond cut quality the grading agency provided for the diamond. While we believe you should always look at this value, we recommend relying on StoneAlgo's Cut Score as it provides much more granularity.