The process of diamond colour grading reveals the inherent beauty of each individual stone. Under meticulous observation and careful comparison, gemologists assess both natural and lab-grown diamonds to determine their colour grading which appears on their corresponding certification. Diamonds range from colourless to light yellow - with colourless diamonds being considered the rarest and the most coveted in the world of engagement rings and fine jewellery.
To distinguish the colour of a diamond, the Gemological Institude of America (GIA) developed the diamond colour grading scale used by the industry today. Colour grades are specified by comparing an individual diamond against a master set. This globally accepted standard for accessing the quality of a diamond will appear on all GIA, GCAL and IGI certificates as part of their detailed analysis. Diamond colour is a significant determinant of a diamond’s value and appeal and is one of the all important 4C’s in which diamonds are assessed. Diamonds are also available in more rare hues such as blue, green, pink and red. But for the purposes of explaining the colour scale - we are looking at white diamonds in this article. To evaluate the colour of a loose diamond, it is first placed face-down to be observed at all angles. Gemologists use a set of master stones which represent each specific colour grade on the GIA scale in which they compare the loose diamond against.
Through this careful observation and comparison they can assign a colour grade outcome which is then listed on the diamonds certificate. It requires a keen eye and expertise to determine this precise colour grading. Natural and lab-grown diamonds are both assessed under this same criteria. There are strict guidelines for the lighting, the observation techniques and the master stone comparisons for a precise evaluation. The colour grading process is performed in a controlled lab environment, placing a loose diamond under consistent and standardised lighting. Diamonds are examined first face-down, then assessed at all angles. Viewing the diamond upside down shows the truest colour of the stone. From above the cut will begin to influence the colour of the stone as it refracts and disperses the light. Some diamonds might exhibit uneven colour distribution and appear inconsistent with their overall colouring.
Diamonds are always graded as loose stones and never graded within a ring setting.
This is due to the fact that they are highly reflective and mirror their environment. Meaning inside a Gold or Platinum setting they will reflect the metals and create an inaccurate grading.
Each letter grade represents the measure of how colourless the diamond is. Diamond colour along the GIA scale ranges from D (colourless) to Z (yellow or brown). The grading system determines that:
DEF graded diamonds are colourless
GHIJ graded diamonds are near colourless
KLM graded diamonds display faint yellow hues
NOPQR graded diamonds display very light yellow hues
A diamond graded D is the purest and most sought after as they exhibit the least amount of colour. The absence of colour allows light to pass through a diamond unobstructed, to create the most brilliant and captivating sparkle. Diamonds graded H or below begin to display a slight yellow hue which is the beginning of the more undesirable portion of the colour scale. The colour of a diamond can enhance or detract from their brilliance.
Colourless or D graded diamonds are the highest quality and value. D coloured diamonds demand the highest prices and are the rarest available on the market. To the untrained eye the differences between higher grade colours (D,E,F) are more apparent in the price rather than any visible variances.
Brilliant Cuts (Round, Oval, Pear, Marquise, Radiant, Princess) are the most forgiving when it comes to a diamond’s colour as their triangular and kite shaped facets will subtly conceal any hues with a glittering sparkle. A diamond’s colour will be more pronounced with any Step Cut shapes (Emerald, Asscher, Baguette) which will show more of their true essence. There is no place for colour and inclusions to hide in a step-cut with their long open faceting showing deep within the stone.
The aim and most desirable option for our clients is finding a diamond with the most colourless appearance within their budget. The most popular choices fall in the colourless (D,E,F) and near colourless (G,H,I) range. Grading of a diamond's colour is part of the diamonds 4C’s, to discover their beauty and unique characteristics.
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