What exactly is diamond colour?
While most people think of the classic, transparent diamond, which happens to be the rarest and most valuable, the colours of diamonds actually range from transparent all the way to a brownish colour. There are different saturations of diamond colours and tones.
The Gemological Institute of America, known as the GIA for short, is the most commonly used system for evaluating diamond colour. They’ve created something known as the “GIA Color Grade Scale”, and it has placed a grading system on the many different colours and shades of diamonds, classifying them into 22 letter grades.
How Diamonds are Graded
The Gemological Institute of America has certified diamond colour grades as “master colour comparison” diamonds. When a diamond is being graded, it is compared against these master colour comparison grades, to find the shades that match it most closely. The diamond that is being graded must be thoroughly cleaned and all oil must be removed from the surface before being examined since even small amounts of dirt or oils on the surface of the diamond can alter the colour.
A line of master colour comparison diamonds or shade chart is set up, with each grade placed about one inch apart, ranging from the lightest and highest graded D shade to the darkest, graded Z diamonds. The diamond colour that is being graded is moved from the left side of the comparison units to the right until it matches one of the shades.
Diamond grading should take place in a colourless environment, using a balanced fluorescent light source that has a filtered, cool white sun like a ray. The room where the grading takes place is dark, all except for the special grading light, in order to obtain the most accurate grading of the diamond colour.
Fluorescence of Diamonds
Yet another consideration when considering the diamond colour is diamond fluorescence, and how it will affect the actual appearance in the diamond colour. Fluorescence causes some diamonds to change colour when viewed in our every day, ultraviolet lighting, as well as under fluorescent light bulbs.
When a diamond colour is graded, the strength of the fluorescence of that diamond must also be indicated. It may be considered to be strong, moderate, or weak fluorescence, and the reports must also indicate what colour the diamond will change due to the fluorescence. The reason for this is when people are in the jewellery store, looking at diamonds in the special lighting of the store, they may all appear to be colourless, transparent diamonds. When you purchase a diamond and get it home under normal lighting, you could find your diamond is yellowish in colour!
You can ask your jeweller to provide grading documentation and information about the fluorescent value of a particular diamond before purchasing, to make sure that you will be happy with the diamond you buy. Many jewellers also can show you the diamond under different lighting conditions, which will enable you to fully appreciate the beauty of the diamond before you buy it. Some individuals like a diamond colour with a darker shade, while others are insistent on the transparent diamond colour. The diamond colour is one of my personal preferences, so be sure to do a little research before making your final selection.
