A cut above: The savvy shopper's guide to diamonds

It has been more than half a century since Marilyn Monroe breathily informed us that ''diamonds are a girl's best friend'' in the iconic 1953 film ''Gentlemen Prefer Blondes''. We can forgive Marilyn for those eye-searing pink silk gloves - because she got the most important accessory right! Diamonds never go out of style!

Diamonds are the most expensive gemstones in the world. Not surprising, considering the amount of time, pressure and intense heat required for the natural formation of these dazzling little rocks.

18ct Gold Vintage Ring With Diamonds

Before succumbing to your inner magpie and snatching up just any stone, remember that not all diamonds are created equal.

When deciding on which diamond to buy, you have a choice (largely dependent on the size of your wallet) between two types: natural or synthetic.

While it is possible to produce flawless artificial diamonds at a much lower cost, the real deal is often preferred - precisely because natural impurities or ''birthmarks'' are what makes these gems unique. White diamonds (classified as Type I) are the most common naturally occurring diamonds, but you also get rare coloured diamonds (Type II) in a hue of yellow, pink, blue or green.

Next to consider is the diamond's shape. The most popular cut is Round, but the more adventurous out there can opt for ''fancy'' shapes like Oval, Emerald, Princess, Heart, Pear, Trillion, Marquise or Baguette.

Being well-versed in the 4 C's of diamond selection is also very important.

Colour: Diamond colours are graded from from D (colourless) to Z (light yellow).

Clarity: Diamond clarity is affected by natural imperfections or ''inclusions''. These are often invisible to the naked eye, so be sure to check with a reputable jeweller.

Cut: A good cut will improve a diamond's brilliance. Always opt for the one with the most sparkle.

Carat: Size isn't everything! A smaller diamond with a good cut and clarity may prove to be a better buy than a flawed stone with a higher carat weight.

These 4 C's are your guide to buying a new ''best friend''!