What is the 4C?

The Gemological Institute of America (GIA) developed the Rule of Four (4C) to simplify the complicated grading of diamonds. Diamonds are graded according to their colour, cut, clarity, and carat weight. These four factors determine the value and rareness of a stone.

Diamonds are graded on a scale of 23 shades, ranging from the icy white D (colourless) to the warmer Z (pale yellowish). Completely colourless diamonds are scarce, but the difference between shades can be very subtle. Unlike coloured diamonds, colourless diamonds do not absorb light falling on them. However, both are precious and, when given with love, priceless.

The cut of a diamond defines its sparkle. Giving the stone a graceful shape brings out what is most beautiful about the stone and determines how it reflects light. An expertly cut diamond with perfectly symmetrical facets can be even more expensive than a slightly larger or rarer diamond.

As a diamond forms, it can develop specific mineral inclusions, which vary from stone to stone. The fewer these, the more precise and more valuable the diamond. Even if the inclusions are invisible to the naked eye, they can affect light reflection and refraction.

A carat of diamond is a measure of weight equal to 200 milligrams. Measurements shall be taken to the nearest hundredth of a decimal place to ensure complete precision. However, weight in itself does not determine the value of a diamond. For example, the price of two one-carat stones can vary considerably if their clarity, colour, and cut are taken into account. Large diamonds of unsurpassed quality are, therefore, scarce and considered extremely valuable.