Just like any two people, no two diamonds are alike; the faceting and variation between each stone make each diamond’s beauty distinct. Gemological labs such as GIA (Gemological Institute of America) and IGI (International Gemological Institute) use systems to describe a diamond’s appearance and officially grade its quality. A diamond’s grade is determined by the 4Cs: cut, colour, clarity, and carat.
These are the four defining factors that are important to consider when purchasing a diamond, because many of the factors that affect its value might not be apparent at first glance. For diamonds sold online, it can be even trickier to understand the value of a diamond from just an image, and it's best to check its grading certificate to make sure you're making a fair purchase. Let’s take a closer look at each of these categories.
Colour
Colour
Colour
Colour refers to the natural presence or lack of colour visible within a diamond. If a diamond appears slightly yellow, it is said to have more colour. Typically, the clearer (or more colourless) the stone is, the higher its value.
Colour is usually an indication that different trace elements were present when the diamond was being formed. Diamonds with more colour will exhibit a pale yellow or pale brown tint, which reduces their colour grade and value. Subtle colour won’t always take away from the beauty of a diamond — it may even make it more unique. However, the more colour a diamond has, the more difficult it is for light to pass through it, which can result in a darker or dull stone.
When light enters a clear and colourless stone — it passes through easily, resulting in more fire and brilliance. In terms of colour, lab grown diamonds are in a completely different playing field to mined diamonds. In the controlled conditions of a laboratory, the mineral contamination that causes colour in a diamond is far less likely to happen, leading to a significantly greater proportion of colourless diamonds.
So while mined diamonds can fall anywhere on the D – Z scale, with D – F being an incredibly rare and expensive colour grade, the controlled conditions of lab diamonds means that they are usually graded J (near colourless) or clearer, with D – F being generally the preferred range.