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The cut of a diamond does not refer to the shape of the stone, but rather it's proportions and symmetry. A well proportioned diamond will allow light to reflect through the crown (top) of the stone, creating that beautiful sparkle. How the light is reflected is down to how the facets (a flat polished surface on any side of a diamond) have been angled.

The diagram on the left shows how light passes through diamonds. If the diamond has been cut too shallow or too deep, the light will escape through the bottom of the stone or out of the side, reducing its sparkle. In an ideal cut diamond the light will reflect off the facets at an angle, which allows it to escape out of the top.



One of the factors in grading the quality of a diamond is its colour, this is done using the GIA (Gemological Institute of America) scale of colour.

At the top of the scale you have the letter D, which represents a colourless diamond, the scale moves down with the increasing presence of colour through "near colourless", "very faint/faint yellow", "light yellow" and "yellow". Here at Richard Sinton Jewellers we strive to provide the best quality diamonds to our customers and so, the majority of our diamonds are D-H in colour. The differences between colourless and near colourless diamonds are very subtle and can be hard to see with an untrained eye however, these small differences make a large impact on the price of the stone.

Why does the scale start at letter D? The scale starts at D because prior to the GIA system, diamonds were graded with letters A,B and C but this grading system was inconsistent and inaccurate.



Another factor which affects the quality and price of diamonds is the clarity.

Similarly to the colour of a diamond, the clarity is graded on a GIA scale. This scale shows how many inclusions can be seen in the stone, these inclusions are natural particles of carbon. Diamond cutters make every effort to cut the stone in a way that will hide the inclusions however, it is not always possible depending on how many inclusions a stone contains.

Almost all diamonds are graded using the GIA system under 10x magnification, which is shown in the diagram on the left.


Carat Weight

Diamonds are sold by carat weight more than any other factor however, depending on the colour and clarity of the stone, diamonds that measure the same carat weight can differ in price. A 1.0 carat diamond is weighed at 0.2 grams.

At Richard Sinton Jewellers you may find carat weights such as 0.23 or 0.71, this is because stones that fall just under the desired 1/4, 1/2 and 1 carat weight are often less expensive. This means we can provide a better price for our customers.