Understanding Diamond Cut


Think back to middle school science class when your teacher showed you how a prism breaks white light into all the colors of the rainbow. A prism does that because it is cut with the correct angles to refract the light, breaking up the white light into its beautiful spectral colors.

A well-cut diamond does the same thing. White light enters the top of the diamond and then shoots back out as the separated colors of the rainbow. When jewelers talk about “fire,” or “light performance,” this is what they mean.

When people oooh and aaah about the beauty of a diamond, it's almost always because it's well cut to sparkle like crazy.

Cut is all about how much light a diamond sends back to your eye as dazzling reds, oranges, yellows, greens, blues, indigos, and violets. Cut is the biggest factor in whether a diamond sparkles and looks alive, or whether it looks dead and lifeless.

Color and clarity have far less impact on a diamond’s beauty than many people believe. When thinking about the 4 Cs, remember this: Cut is king.

KNOWING GOOD CUT WHEN YOU SEE IT
The short explanation is that the diamond should sparkle like crazy under a variety of light sources. It shouldn’t just sparkle under the jeweler’s showroom lights; it should sparkle on a sunny day, and it should sparkle in the sexy evening light of a candle-lit dinner.

For the longer, more technical answer, let’s use round-shaped diamonds as an example.

The standard cut for maximum sparkle in round diamonds is called “Ideal Cut.”

Ideal Cut diamonds are cut with mathematical precision to return maximum light and sparkle to your eye. The result is a bright and gorgeous diamond.

The diagram below shows how light behaves in diamonds that are cut too shallowly, or too deeply. Poorly cut diamonds will look dark, dull, and lifeless.


If you want to take this one step further, many jewelers have what’s called a “proportion scope.” This shows if the diamond is cut to ideal proportions. The Ideal Cut diamond from the diagram above would look like this under the proportion scope:


This symmetrical layout of “hearts” and “arrows” is the standard pattern you will see in an Ideal Cut diamond. Diamonds cut in the correct proportions, will return massive amounts of light to your eye and be absolutely beautiful.

Cut is king. A jeweler who is on your side will tell you about the importance of cut. A jeweler who either doesn’t know what he’s talking about, or is trying to run up your price tag, will push you toward a “high color, high clarity” diamond.

High color, high clarity diamonds are not right for 95% of shoppers, and they will not give you the most value for your money.

Do not skimp on cut.

Because, if you purchase a well-cut diamond, color and clarity are where you can save a lot of money by shopping smart.

NEXT: Read about Diamond Color & Clarity