How to choose a diamond: the four Cs explained

Start with the four Cs

Diamonds are described by four qualities, known as the four Cs: cut, colour, clarity and carat weight. Together they explain why two stones of the same size can look and cost very differently.

Cut

Cut describes how well a diamond has been shaped and polished, and it has the biggest effect on sparkle. A well-cut stone returns light through the top, creating brilliance and fire. A poorly cut one leaks light and looks dull, even if its colour and clarity are excellent. If you can only prioritise one C, make it cut.

Colour

Colour is graded from D (colourless) to Z (light yellow or brown). Stones graded D to F are the most colourless, and G to J look white to the eye, especially once set in a ring. Many people find the G to H range offers excellent value.

Clarity

Clarity measures tiny natural marks called inclusions. Grades run from flawless to included. A stone graded VS1 or VS2 has inclusions that are very small and not visible without magnification, which makes it a popular balance of beauty and price.

Carat weight

Carat is a measure of weight, not size. One carat equals 0.2 grams. Two stones of the same weight can look slightly different in size depending on their cut. Prices rise sharply at round numbers such as one carat, so a stone just under can offer noticeably better value.

Ask for a grading report

An independent report records a diamond's grades so you can compare stones with confidence. Whenever we have one, we list its details on the product page.

A simple way to decide

• Choose an excellent cut first.
• Choose a colour that looks white in the setting you prefer.
• Choose a clarity where inclusions are not visible to the eye.
• Let carat weight follow your budget.