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Diamond Guide

Diamond Buying Guide: Beyond the 4C’s

If you could do one thing before you buy a diamond

It is this: remember that you are buying a diamond and not a paper certificate

Most people are familiar with the 4C’s associated with the quality of the diamond, but there are so many other variables that determine a diamond’s brilliance, beauty and ultimate value. There are 58 cuts in a traditional round brilliant cut diamond, so realistically there are 58 times that man alone can make a mistake in getting proportions right, never mind the millions of years that Mother Nature was in charge of creating the rough. Even a physicist would have a hard time choosing a diamond based on the written specifications of a GIA certificate. Gemological reports are very helpful, but they are simply a variable in choosing the right diamond.

Diamond Jewelry
Diamond Jewelry


A diamond’s transparency can be affected by inclusions, irregular and distorted crystal growth, or, most commonly, clouds (a cloud is a group of minute inclusions invisible to 10x magnification). Two diamonds with identical grading can have dramatically different levels of transparency and will therefore be valued quite differently.

Type or Colour of Inclusions

Even in higher VS clarities, black inclusions can contrast against a colourless diamond and distract the eye. Here’s an example: if a VS2 diamond has a black center inclusion and a SI2 diamond has a scattered white inclusion off to the side. The SI2 diamond will be visually more appealing and, best of all, cost a fraction of the price.


When most people think of a diamond’s colour, they think of the colour grade as assigned by GIA, D through to Z. However, there is a different type of colour that must be considered when buying a diamond. This is a diamond’s hue. Some common hues that negatively affect a diamond’s beauty are brown, grey, green and off-white. These diamonds will appear dull and less lively. Since GIA does not make any special distinction between hues in colour grades higher than K, their effect on a diamond’s beauty can only be confirmed by visually inspecting a diamond.

Diamond Jewelry
Diamond Jewelry


Just as a diamond’s facets reflect light to create brilliance and fire, they can also reflect a diamond’s inclusion to create multiple “mirrored” or “false inclusions” throughout a diamond. Since GIA does not plot the locations of these reflections, a diamond will look noticeably different from what a report indicates when its inclusions reflect. A diamond’s reflection can adversely affect its beauty while still having a higher grade on the GIA scale.

Weight and Size

To hold a certain weight range and maximize a diamond’s per carat price, a diamond cutter will sometimes “hide weight” by fashioning an extra thick girdle or by cutting a diamond deeper than it should be. These diamonds will look smaller than a diamond of identical weight that is well proportioned. Therefore, when considering a diamond’s carat weight, a diamond buyer should also consider its millimeter size to be sure the diamond “looks its size.” A high Clarity or Colour grade on a certificate does not guarantee a diamond’s beauty or value. The only true way to get the best diamond is by seeing it in person.

What sets us apart is our people

The only way to choose the best diamond is to hand select them with expertise, so that’s what we do. All of our diamonds come with full certification, but they are also hand selected by our buyer who has 30 years of experience. He hand picks and hand matches every diamond in our showcases. Island Jewellers has the connections of a major diamond retailer but the ability to be as selective as a family owned business. Established in 1978, Island Jewellers has the largest selection, highest quality and best value on island that is why we are considered locally to be “The Only Place for Diamonds”.

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