A diamond’s value is determined by several criteria, including colour. Diamond colour scales range from D to Z. A D-graded diamond is colourless, with no hue, and thus is the most valuable.

Diamonds are also graded on the quality of cut, which is defined as follows: Ideal | Premium | Very good | Good

The cut refers to the diamond's reflective qualities. It's important not to confuse "cut" with "shape". Shapes include pear, princess, trilliant, marquise, oval, cushion, emerald, baguette, trapeze, radiant and heart.

Diamond quality is also determined by Carat weight.

The size of a diamond does not reflect its weight.

Diamond prices increase exponentially according to the weight of the stone, which is calculated in levels. There can be a huge difference between a 0.89 carat diamond and a 0.9 carat diamond, as these two values belong to different levels.

Because large stones are rare, price increases are not proportional to weight: a 1.5 carat diamond is three times the weight of a 0.5 carat diamond, but the price can be five to seven times higher than a 0.5 carat stone.

All diamonds come with a certificate of authenticity, which documents a diamond's unique attributes based on an independent gemmology lab analysis carried out by certifified diamond merchants.

While there are several different diamond grading laboratories with their own criteria and grading methods, they all work within the same set of parameters when grading a diamond's dimensions and attributes.

• The GIA (Geomogical Institute of America)
• The HRD (Belgium's Diamond High Council)
• The International Gemological Institute (IGI) in Antwerp

Diamonds are tough yet fragile stones.

• 1. To ensure a diamond keeps its sparkle, clean it in hot soapy water a couple of times a year.
• 2. Use a gentle, non-abrasive detergent and soft bristle toothbrush to gently remove encrusted dirt from set diamond jewellery.
• 3.

N.B.: Diamonds can withstand being cleaned in very hot water.