Colour Grading

Colour is one of the Four Cs of grading diamonds, but just how important is it to you? Learn all you need to know about colour, from D to Z.

Beautiful, fiery, rare and scintillating... diamonds are all these things, but in terms of colour, they can be a confusing lot. That's because the ideal diamond, the one with the highest "D" colour rating, is in reality totally colourless. It's this very fact of colourlessness that makes it valuable. When a diamond have the slightest shade of yellow or brown, its value drops quickly.

At the same time, a diamond in a vivid colour is known as a "fancy" diamond and fetches top dollar among aficionados and collectors. This is especially true for bright yellow "canary" diamonds and the glorious pastels of pink and blue diamond.

There are three categories of diamonds: white diamonds, the kind most people want in engagement rings and jewelry; fancy natural coloured diamonds, those beautiful rarities reserved for special pieces and one-of-a-kind designs; and irradiated diamonds, stones given fancy colours with a little help from nuclear science.

Whitest of the White

If you are looking for a diamond for an engagement ring or pendant, your goal is probably to find one that is the whitest white. Of the famous Four Cs of diamond valuation, many experts cite colour as the number one consideration. Diamond colours are graded on a simple system, beginning with "D" for colourless and travelling down the alphabet to stones with traces of colour to stones with visible shadings. By the time you reach the middle, all the way to final stages of the alphabet (M-Z), you've found stones with poor colour.

Whiter the colour, better the diamond's ability to reflect and refract light. When white light enters the diamond, part of the ray is reflected back to the observer's eye, but the rest penetrates the stone. Refraction happens when the ray is deflected toward the center of the stone, then bounced back to the surface.

How do you determine which white is whitest? Because colour differences can be so subtle they are impossible to determine by the untrained eye, diamond experts compare your diamond with others. The best way to judge a diamond's colour is to look at it on a white background. To grade a diamond, gemologists often place it next to another diamond that has been previously graded.

As important a consideration as colour is, know that it is just one of the "Four Cs" that determine a diamond's quality. The others, carat, cut and clarity, all play vital parts in assessing a stone's value. A "D" colour grading means a lot less if the cut is poor or the stone is very small.