What You Need to Know Before Buying a Diamond

Hoping for a Christmas or New Year marriage proposal? Does your other half need a not-so-subtle nudge in the right direction?

Will you be the one doing the knee-bending? Want to make sure you're savvy enough to put any swindlers off trying to sell you a Christmas cracker prize? 

Or maybe you just feel like treating yourself to a bit of diamond-based 'frosting'?

Luckily, there exists an internationally recognised system for grading diamonds, developed by the Gemological Institute of America (GIA), which can help you distinguish between a rock that demands a 'yes' and bargain basement rubble.

Read on for my guide to the '4 Cs': carat, colour, clarity, and cut. 

Carat

There are moments in life when it's OK, girls, to be generous and allow ourselves to admit that size doesn't matter. 

But when it comes to diamonds, I'm sorry - SIZE MATTERS. 

The carat weight measures the mass of the diamond, with one carat about equal to 200 milligrams. For diamonds which have a mass of less than one carat, the size is described using the 'point' unit. A 'point' is one hundredth of a carat so, for example, a diamond described as '70 points' is actually 0.7 carat in size.

For diamonds that are more than one carat in size, they are, I assume, described with such technical terms as 'what a beauty' or 'that's a big 'un.

Colour

Size alone cannot dictate the standard or value of a diamond. A stone may be bigger but of a lower quality in other aspects.

The highest grading in terms of the colour of a diamond is, in fact, colour-less. Diamonds of this standard are graded 'D' with a sliding scale down to 'Z' for stones showing increasing levels of colour.

The odd thing is that the hue and intensity of the colour can have an incremental or detrimental effect on it's monetary value. White diamonds showing a yellow tint will be regarded as lower quality, however intense pink or blue diamonds are considered extremely valuable.

And I know what you're dying to ask: why does the grading start at 'D'? That's a fantastic question.

The reason is that before GIA introduced their system there were lots of different grading systems being used (ABC, 123, etc). GIA decided to begin their grading at 'D' in order to avoid confusion and stand out from the crowd. Such trend-setters, hey? 

Clarity

Clarity is a measure of the internal defects of a diamond. These defects are called 'inclusions' and can be foreign material or structural imperfections inside the stone. A number of factors including the number, size, colour and location of inclusions affect the clarity of a diamond, but many are only discernible when studied under a microscope.

Clarity grades are as follows: IF (internally flawless), VVS1/VVS2 (very very slight inclusions), VS1/VS2 (very slight inclusions), SI1/SI2 (slight inclusions, may be visible to the naked eye of a professional), I1/I2 (inclusions visible to Joe Bloggs' naked eye).

The '1' or '2' relates to the position of the inclusion: '1' if it is to the side, '2' if it more central.

According to Wikipedia, only 20% of diamonds mined have a clarity rating high enough for the diamond to be considered appropriate for use as a gemstone. The other 80% are kept for industrial use. So, if your other half does show up with something that looks like it fell out of a Christmas cracker, remember - at least it made it into the cracker in the first place.

Cut

The cut of a diamond is not merely the shape of the finished product, but also accounts for the manner in which the stone has been shaped and polished since it's humble beginnings as a misunderstood pebble. The level of workmanship which goes into maximising the amount of light reflected by the gem, and therefore it's resulting sparkle, is not to be sniffed at.

Two diamonds can have the same shape but one may be cut with much more precision, making it a better quality stone overall. An excellent cut will maximise the internal reflection of the light, therefore appearing to give the stone more sparkle. The angles of a poor cut will mean light is badly reflected within the stone, and limit its sparkle.

So, now you have no excuse not to leave the jewellers with the best diamond your intensively-scrounged pennies can afford you.

And if you're still struggling, head over to Eric Ross in Hatton Garden. I happen to be married to someone there who may be able to help you out.

I did not receive compensation of any kind in return for this post. All views are my own and this post was written on a voluntary basis.

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