After 'cut', colour is acknowledged as the foremost characteristic of diamond and is perhaps the most misleading of the terms used to describe diamond. It actually refers to the amount of yellow tinting and the less colour a diamond has, the higher grade it will achieve.

The yellow hue running through most diamonds indicates the presence of trace nitrogen within a diamond's molecular carbon structure. Whilst the colour variation between two different diamonds may be indistinguishable to most people, it can affect the respective values dramatically, this makes an understanding of diamond colour grading essential.

Using the GIA (Gemmological Institute of America) standard colour grading system which is adopted universally within the jewellery industry, Hearts of London diamonds are graded as:

  • D (Colourless)
  • Completely colourless diamonds that are of highest possible quality. Such stones are very rare.
  • E (Colourless)
  • Often mistaken for D grade diamonds, these appear colourless and are also rare.
  • F (Colourless)
  • Diamonds that appear colourless with only the faintest trace of colour. These stones offer great value for money.
  • G (Near Colourless)
  • These diamonds are the highest quality 'near colourless' stones. Their colouring is only usually detectable to a trained gemmologist.
  • H (Near Colourless)
  • These diamonds have a very slight tint that cannot easily be detected when set or viewed from the crown (top) facet.
  • I (Near Colourless)
  • A slightly yellow tint is present in these diamonds but they offer outstanding value, especially in larger carat sizes.
  • J (Near Colourless)
  • The least expensive diamonds classified as being 'near colourless', these can still display exceptional brilliance when cut correctly.
  • K-Z (Tinted)
  • Diamonds with noticeable colouring and noticeably diminished natural brilliance. These diamonds are not used or sold by Hearts of London.

We only use diamonds with colour grades between D and J (colourless and near colourless) and while those outside these grades may be accepted elsewhere, our commitment to quality ensures that they are firmly rejected. As such, the colouring in a Hearts of London diamond will be virtually invisible. In addition, we will always state the lower colour grade should a diamond fall between two classifications.

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  • Make an informed choice when selecting a quality diamond. Move the sliders to understand how colour and clarity impact upon the look of a diamond.

    Hearts of London only carry diamonds in the 'colourless' and 'near colourless' grades. Furthermore, our loose diamonds are graded and independently certified by totally impartial gemmological laboratories.

Care should be taken when selecting a metal to accompany your diamond. I and J grade diamonds should ideally be set into yellow gold as this can help disguise any light tint. The best results for D to H grade diamonds meanwhile are achieved when using white gold or platinum.

Some diamonds actually glow blue under ultraviolet light. While this fluorescence effect can make them appear whiter than they actually are, these diamonds can also look cloudy or milky in daylight. For this reason, Hearts of London reject diamonds with a strong blue fluorescence.

Selecting a diamond that has a slightly lower colour grade that can provide a significant saving and the colouration can often be disguised with a good, very good or excellent cut, especially where the diamonds exhibits weak or medium strength fluorescence.