The 4 Cs of diamonds

It can be so difficult to choose the perfect diamond. You may find that two stones look very much alike, but have very different values. This can be determined by the four Cs - carat, clarity, colour and cut.

Read on to discover how these four characteristics can affect each diamond.

Cut

Diamonds can be cut in many shapes, from round to fancy. The cut of the diamond determines its brilliance, and a skilled craftsman can release the inner fire and sparkle of a stone with just a few well-placed facets. A well cut diamond reflects light from facet to facet, lighting up the interior of gem.

Carat

The carat is the standard unit of measurement used by jewellers and refers to the weight of a diamond. The word 'carat' is derived from ancient times when gems were measured against the weight of a carob seed.

One carat is equivalent to one-fifth of a gram, and is also divided into 100 points. So a 1/2 carat diamond weighs the same as a 50 point diamond.

Generally the larger the carat, the more rare and valuable the diamond. However, although two diamonds may have the same carat weight, their colour and clarity can differ, affecting the value of each gem.

Clarity

Most diamonds have small, natural imperfections called inclusions. These are known as nature's 'birthmarks' or 'fingerprints' and can look like tiny crystals, clouds or feathers. The fewer the inclusions a diamond has, the greater its clarity and the higher its value.

Inclusions are usually invisible to the naked eye. The number, size and location of inclusions can affect the flow of light through the diamond, causing some of its sparkle to be dimmed.

The clarity of a diamond is graded in one of five categories:

Colour

The most highly prized diamonds are colourless, although most diamonds are tinted with subtle yellow or brown tones. Diamonds are graded from D for colourless, through to Z for light yellow stones. A truly colourless diamond disperses light effortlessly throughout the stone, creating an incredible rainbow of colours - these stones are treasured for their rarity.

Diamonds can also be found in pinks, blues, greens and bright yellows. These are known as 'fancy' gems and are extremely rare and valuable.

Cut

Emerald: This bevelled step cut has beautiful mirror-like facets, which requires the stone to have exceptional clarity. Although not as fiery as a brilliant cut, the 58 facets of the emerald cut offer broader, more dramatic flashes of light

Heart: The heart cut is based on the traditional brilliant cut within a heart-shaped border. The true origins of the heart cut remain a mystery, though it was mentioned as far back as 1665. Symbolising affection and love, heart cut diamond jewellery makes a truly romantic gift.

Marquise: The marquise cut was named in honour of the elegant Marquise de Montespan, mistress to Louis XIV of France, and was said to resemble her smile. The marquise cut is an elongated ellipse with pointed ends, and is beautifully architectural in shape, one reason for its popularity in Art Deco jewellery.

Oval: The oval is a cut used more rarely for diamonds, but this makes it all the more beautiful. A well cut oval diamond can be almost as bright as a round brilliant-cut gem, as it contains almost as many facets in a similar pattern. A well proportioned oval-cut diamond offers wonderful scintillation and inner fire.

Pear: Pear cutting is another variation of the brilliant cut, and is particularly beautiful when used in pendants. Twenty percent of the 100 largest diamonds in the world are pear cut - one very famous example is the Cullinan. Pear cutting works particularly well with diamond, revealing its wonderful internal fire.

Princess: The princess cut is one of the most modern gem cuts available. The cut was developed by
A. Nagy in London, in 1960. Designed to gain maximum brilliance from a square stone, the princess cut gets its liveliness from a series of V-shaped grooves cut into the back of the stone. A well-cut princess stone looks just liking a sparkling star.

Radiant: The radiant cut is a wonderful twinning of the classic emerald cut with the sparkle of the round brilliant. The radiant cut looks stunning as a solitaire, but also looks great paired with trilliant or princess-cut side stones. A radiant-cut diamond should be prong-set at the corners to make the very most of the play of light through its facets.

Round Brilliant: The round brilliant cut is the most recognisable cut of all, and is still the favourite for engagement ring designs. The brilliant cut can be traced right back to the early 1700s, and really allowed gemstones to come into their own. The round brilliant cut is the classic cut that reveals the icy fire and flawless clarity of a diamond.

Trilliant: The trilliant is one of the most unusual cuts for diamonds. This triangular cut has a particularly sharp brilliance reflected amongst its elongated triangle facets. Trilliant-cut diamonds are often used on the shoulders of rings, but make for a truly gorgeous solitaire setting.