Comparing the Different Diamond Colour Grades

We generally think of diamonds as colourless. In reality, though, most diamonds have a degree of colour. A diamond’s colour greatly influences its value and beauty, so it is important to carefully consider a diamond’s colour before you purchase it.

This article contains everything that you need to know about the different colours in diamonds, how they are graded and which colour grades are the best for engagement and wedding rings.

The Colour Scale: Comparing diamond colours

As diamonds are formed deep within the Earth’s mantle, trace amounts of nitrogen mix with the carbon and give the new diamonds a yellow colour.

Diamonds come in various shades of yellow which vary from so light that it is unnoticeable to the naked eye to brownish yellow. The Gemological Institute of America, or GIA, created the standard grading scale used for diamond colour.

The scale begins with the letter D and ends with Z and has the following five categories:

  • Colourless – This category contains diamonds graded as D, E or F. Their colour can only be seen under a powerful microscope.
  • Nearly colourless – Diamonds graded as G, H, I and J are nearly colourless and their faint shades of yellow are rarely noticed by the casual observer.
  • Faint – Diamonds in this category are a distinct, but light shade of yellow and are graded as K, L and M.
  • Very Light – With darker shades of yellow than faint diamonds, very light diamonds are graded from N – R.
  • Light – Light diamonds are the yellowest of all and are graded from S – Z.

Why does the colour scale start with D instead of A?

Years ago the colour grading systems used for diamonds were inconsistent and often inaccurate. Some gem traders used the letters A, B and C to categorize their diamonds by colour. In this system, any diamond that was better than the valuable A category was given two or three A’s to set it apart from the rest. Other gem traders graded their diamond colours with Arabic numbers or Roman numerals, and a few even used descriptive words.

When the GIA decided to standardize the diamond colour scale, they began the scale with the letter D to make it clear that it was completely new and not associated with any of the earlier grading systems.

Which colour grades are the best for engagement and wedding rings?

Each jeweller has their own answer to this question, but we advise our clients to choose diamonds graded from D to I. We have found in our years of experience that these colourless or nearly colourless diamonds are the most beautiful and go well with any precious metal including white gold and platinum.

A final word: Don’t be confused with fancy colours

The diamonds we have been discussing in this article are regular white diamonds. Most of them have a light yellow colour from nitrogen and they are graded using the GIA’s Colour Scale. A small percentage of white diamonds become contaminated with other trace elements besides the nitrogen. These other elements mix with the nitrogen to form new colours, including red, blue, pink and green. Diamonds with these colours are called fancy colour diamonds. They are not graded on a specific colour scale, but rather valued according to the strength and purity of their colour.

fancy coloured diamonds