Most people choose a diamond engagement ring, so it is important to understand how the stones are valued using the 'Four Cs': carat, clarity, colour and cut.

Carat

The size of the diamond. The larger the stone, the greater the carat weight and the more expensive the diamond. There are 100 points to a carat: 1 carat = 0.2g.

Clarity

The marks or inclusions in the stone. Fewer inclusions mean greater clarity, greater brilliance (sparkle) and greater value.

A diamond is viewed under 10x magnification by a professional gemmologist to grade its clarity:

F = flawless. Extremely rare, with no imperfections.

IF = internally flawless. Rare, with no internal inclusions.

VVS1, VVS2 = very, very slightly included. An excellent diamond - contains inclusions that are extremely difficult to see under magnification.

VS1, VS2 = very slightly included. Contains small inclusions that are hard to see under magnification.

SI1, SI2 = slightly included. Contains visible inclusions under magnification.

Colour

The colour of a diamond is graded alphabetically. Letters towards the beginning of the alphabet are the best diamonds, starting with D. Choose stones of H quality or higher (i.e. D/E/F/G/H).

D, E, F: colourless and best
G, H, I, J: near colourless
K, L, M: faint yellow
N, O, P......Z: very light.......light yellow

Cut

The angles and proportions of the stone. A well-cut diamond is not too shallow or too deep and allows the light reflects off the perfectly cut facets.

The grades of cut are excellent, ideal, very good, good or fair.

The shape of a diamond is also often referred to as the cut. This does not generally affect the price - there are many different shapes to choose from.

• Round, oval, pear, princess (square), marquise (oval with pointed ends), emerald (rectangular) and asscher (square with rounded edges) are all commonly seen.
• Round cut diamonds are the most usual and popular.
• A single diamond set alone is referred to as a solitaire.

See also

Visit the Debrett's Wedding Collection for our handpicked selection of the finest engagement and wedding rings.

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