What is Colour?

Diamonds all have colour and that colour can be evaluated on a colour grading scale, with a different scale for fancy grades.

Diamonds are normally thought of as sparkling, scintillating, colourless gems. It is this colourlessness that allows for the incredible and breathtaking play of light that we all have come to associate with the diamond. As you are probably already aware, the colour of diamond is primarily dependent on inclusions and foreign matter within the diamond's crystalline structure. This foreign matter absorbs light, rather than allowing it to pass through unimpeded, thus giving some diamonds varying degrees of colour.

In the normal range of the diamond colour-grading scale, the more colourless a diamond is, the higher it is graded on the scale. In terms of pricing, diamonds with a higher grade will be more costly, while diamonds rating lower on the scale, thus having more colour, will normally prove to be less costly. However, when a diamond has a great deal of colour, or extremely high colour saturation, it may rate the grade of FA, or Fancy. These are the fancy grades of diamond colour, and with these the cost of the diamond may actually go higher than the finest of the D grade of diamonds.

In order to establish which diamonds are which colours, diamond colour-grading scales have been created. Most of these colour-grading scales were not founded with any measure of scientific precision, however, and so are no longer used. Today, there are far fewer diamond colour-grading scales in use, with GIA's being the most used and well respected, allowing anyone to view the results of rigorous testing for colour-grading in a written report for a particular diamond. GIA's grading scale ranges from the colourless D to the highly coloured Z. It is important to be aware that while most diamonds are graded on a scale measuring the varying degrees of their lack of colour, or whiteness, this is not the only sought after type of diamond. There are those diamonds in which various colours are prominent enough to arouse desire for their rarity and distinguished characteristics.

Colour is the effect of light wavelengths stimulating the colour cones in the retina of the viewer. In the case of diamonds, as they are clear objects, the colour that we see from a particular diamond depends on which wavelengths of light's colour spectrum are absorbed, if any, as the light passes through the diamond. The flash of colour that appears within a diamond is the result of the light that is passing through the diamond having some of its wavelengths absorbed by chemical particles trapped within the diamond's crystalline matrix.

In regards to most diamonds, a lack of colour is the most desirable of qualities. What most of us think of when we think of the perfect diamond is of one that shines with a clear brilliance, sparkling and catching the eyes of all who are present. The perfectly clear (or white) diamond is a rarity in the diamond world, and so they carry a large cost. Most diamonds have foreign substances, usually in the form of trace minerals, trapped within their crystalline structure. It is these foreign atoms that absorb certain wavelengths in light's colour spectrum, casting a measure of colour onto and within the diamond, thus producing a certain colour in the diamond. The actual colour of the diamond is therefore dependent on which foreign element or elements are present, as well as the quantity of the foreign element(s) within the diamond's structure.

A diamond's colour is rooted in the earth from which it comes. Diamonds are formed over millions of years, as the result of carbon deposits placed under enormous geologic pressure and incredible heat. Throughout the growth of the diamond, and the diamond's eventual push towards the earth's surface, the diamond is subjected to naturally occurring radiation, geologic movement that can twist the crystalline structure of the diamond, and the potential addition of impurities. During the diamond's formation nearby elements of other minerals are often mixed in with the carbon deposit. As the diamond deposit cools, and the crystalline structure that we recognize as a diamond begins to grow, some of these other minerals become trapped within the growing crystal.

In fancy coloured diamonds, such as in Canary yellow diamonds, where there are large numbers of nitrogen atoms scattered throughout the diamond. These nitrogen atoms absorb light, giving the Canary yellow diamonds their vivid yellow colour. The same goes for all of the other colour diamonds, simply with alternate atoms trapped within the diamond.

The inclusion of foreign atoms is just one way in which diamonds can become coloured during their formation. They can also become coloured due to irregular growth patterns arising from pressure as the diamond is forced to the surface of the earth, as is found in certain pinks and blues. In the case of greens, it is the natural radiation found within the earth that gives them their colour.

Once the diamond is fully formed and has been forced to the surface of the earth, these trapped foreign objects, such as trace mineral deposits, gases and liquids, become a part of the diamond's crystalline structure. The diamond's crystalline structure is clear, or colourless, and so does not have the ability to absorb wavelengths of light. This is why they are so bright and are able to glitter. It is trapped objects, such as nitrogen, which absorb certain light wavelengths, making the diamonds have colour.

Much of the newly found interest in fancy colour diamonds is due to the discovery of a relatively large load of pink diamonds in the Argyle mine in Australia. While the quantity of pink diamonds coming out of the mine is still miniscule in comparison to the quantity of other diamond types, it is still far more than had been available for years. Of course there is another aspect that needs to be understood concerning the current interest in fancy coloured diamonds, and that is the exclusivity of fancy coloured diamonds. Fancy coloured diamonds are far more rare than any other diamond type. It is this rarity that adds to their value, as those who possess a richly coloured diamond hold a king among kings in the gem world.

Tips on Colourless Diamonds

It is important to be aware that as you step down the colour grade scale, the diamond's overall cost will decrease. It is also important to note there is a significant reduction in cost per carat as you move from D to E, and from F to G, and so on. Knowing this, you should carefully and honestly assess what grade of colour you will be happy with. Always keep in mind, the majority of the untrained population can hardly distinguish the difference between a GIA G and H, and likewise a GIA F and G, so if they look the same a letter grade difference in colour could translate to hundreds of dollars in savings.

Finally, consider the setting of the diamond itself. Once the diamond is set its level of colourlessness can be enhanced or detracted from, depending on the metal used for the setting and the size of the diamond. A well-chosen setting can make a diamond with faint yellow colouring appear to be colourless. In other words, a white metal can enhance warm yellow tones in a diamond, whereas yellow gold can cause a diamond to appear more colourless than it actually is.