An in depth look at the colour of a diamond

COLOUR

When selecting a diamond, colour is a crucial factor that affects both its appearance and value. Unlike many coloured gemstones, diamonds are typically valued for their absence of colour. The less colour a diamond has, the rarer and more valuable it generally is. This guide focuses specifically on the colour grading of colourless diamonds, which differs significantly from the grading scale used for coloured diamonds.

THE SCIENCE BEHIND DIAMOND COLOUR

A chemically pure and structurally perfect diamond has no hue; it is completely colourless. This perfect state is extremely rare in nature. Most diamonds contain trace elements or structural imperfections that can impart subtle colours. For instance, the presence of nitrogen can cause yellowish tints, while boron can result in a blue hue.

These trace elements are typically present in very minute amounts, and their effect on the diamond's colour can range from barely perceptible to noticeable even to the untrained eye. The grading of a diamond's colour involves evaluating these subtle differences to determine its overall hue and value.

ASSESSING COLOUR

Diamonds are graded on a colour scale established by the Gemological Institute of America (GIA), ranging from D (colourless) to Z (light yellow or brown). Here’s a breakdown of the colour grades:

  • These diamonds are extremely rare and have no detectable color, appearing icy and brilliant.

  • Slight colour is noticeable only when compared to higher-grade diamonds, offering a great balance of quality and value.

  • Diamonds in this range have a faint yellow or brown tint that can be noticeable to the naked eye.

  • These diamonds have a noticeable light yellow or brown hue.

  • Diamonds in this range have an obvious color that is easily visible.

Choosing the Right Diamond Colour

  • Higher colour grades (D-F) are rarer and more expensive. Near colourless diamonds (G-J) offer great value while still appearing colourless to most observers. Faint colour diamonds (K-M) can be a budget-friendly option, especially when set in yellow or rose gold.

  • Larger diamonds (above 1 carat) tend to show colour more than smaller ones, so in larger stones, it may be beneficial to opt for a higher colour grade to ensure the stone appears as colourless as possible.

  • Different diamond shape can hide colour better than others. For example, round brilliant cuts reflect more light, masking subtle tints, while fancy shapes like emerald or pear cuts might show more colour.

  • If you are choosing a white metal setting like platinum or white gold, these metals highlight the diamond's colour, so selecting a higher colour grade is recommended. Conversely, yellow or rose gold settings can mask slight yellow tints and give the stone more warmth.

  • If your ring features side stones or is part of a trilogy or toi et moi setting, ensure the center stone’s colour matches the side stones. Discrepancies in colour can be more noticeable in such designs, so matching is essential for a cohesive look.

  • Balance the diamond’s cut, clarity, and carat weight, as these factors also affect its appearance and value. A well-cut diamond can appear more brilliant and mask slight colour tints. Prioritizing cut quality will help reflect light better, making colour less noticeable.

Fancy Colour Diamonds

While the traditional color grading scale applies to colorless diamonds, fancy color diamonds operate on a different grading system. Fancy color diamonds include a variety of hues such as blue, yellow, brown, pink, green, and red. These diamonds are highly sought after for their unique and vivid colors.

Fancy color diamonds can be naturally occurring or lab-grown:

  • Blue: Boron

  • Yellow, Brown, Orange: Nitrogen

  • Green: Radiation

  • Pink, Red: Structural anomalies caused by intense pressure