Diamonds “are a girl’s best friend” or so Marilyn Monroe sang in “Gentlemen prefer blondes”.
So what makes a good diamond? Well, a diamond’s quality is usually measured with the four “C’s”;
1) Carat. This is simply a measurement of the weight of a diamond with 1 carat equalling 200mg. Interestingly the term carat derives from the ancient Greek name for the Carob seed which was thought to sufficiently uniform to use as a measure for gemstones!
2) Clarity. Clarity relates to the purity of the diamond and whether there are inclusions or blemishes within the stone.
3) Colour. 
Diamonds are often valued by how colourless they are. The absence of colour enables white light to reflect and diffract better and to give that sparkle, often referred to as “fire”.However some diamonds naturally occur with strong blues and pinks and these extremely rare diamonds command high prices. Sothebys recently sold the Apollo and Artemis earrings for £44.4m.
4) Cut. The diamond cut is probably the most important of the four “C’s”. The cut is a reference to the diamond’s reflective qualities enhanced by the overall shape.
If I was ever allowed to cut a raw diamond, it would probably end up dull and lifeless but a well cut diamond will bounce light through the “table” and reflect from one side to the other and back out again. This light is the brilliance associated with diamonds and it is this flashing, fiery effect that makes diamonds so mesmerising.
Cambridge jeweller, Sarah Palmer, is currently exhibiting a collection of her 18ct reticulated gold rings which show the different diamond cuts. 
From left to right; Princess, Trillion, Brilliant (x2) and Marquise cut diamonds.
Visit Primavera and enjoy what is probably the largest, independently owned jewellery collection in the UK. You might even take something sparkly away with you.....