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Goldsmiths Guide to The Four C's

Diamond Guide

As an engagement ring or wedding band is an investment, it's important to be sure that you have the highest quality of diamond to suit your needs.

The Four C's is the term given to help you understand the quality of the diamonds in an engagement ring or wedding bands.

A guide to diamonds


Colour of a diamond helps determine the cost of the ring it is set in. With the highest quality diamond being colourless, graded D on a scale D - Z, colourless diamonds are highly sought after. There are shades of near colourless with a slight yellow or brown hue that are still considered good quality diamonds, though as they are not colourless, this is reflected in the overall cost of the ring.

A recent trend has seen coloured diamonds being the stone of choice, adding variety and modernising a classic engagement ring. Coloured diamonds can be found in a wide variety of shades: blue diamond, pink diamond, yellow diamond, grey diamond.


Clarity outlines the number of flaws and imperfections of a diamond. While it is natural for most diamonds to contain some inclusions, most are invisible to the eye. Our aim at Goldsmiths is to showcase rings with minimal inclusions and to ensure the price fairly reflects the number of inclusions it contains. To help with this, we offer a chart to help you understand the grade of clarity when viewing our engagement rings online and in our showrooms.

A guide to diamonds


Carat is the measurement of weight given to a diamond, in similar way a bag of sugar may weigh 1kg or 500g. The heavier the diamond the most valuable it is, as it is most common to source stones the smaller their size. The carat of the ring combines all matching stones in that ring, so a diamond trilogy ring carat will be the sum of all three diamonds.


Cut: describes the shape of the diamond as crafted by a specialist diamond cutter. It is shaped symmetrically, cutting lines and angles into the ring that showcase the light, and beauty of the diamond. Often a diamond of a lower carat can be crafted with an exceptional cut to maximise the brilliance of the stone.

Some of the types of the diamond cuts are round brilliant cut, princess cut,emerald cut, oval cut and cushion cut.


Some diamonds carry a certification that includes an analysis of their dimensions, clarity, colour, polish, symmetry and other characteristics. The certificates serve as proof that they have undergone an unbiased, professional examination, and that they can be traced back to suppliers who comply with the UN-mandated Kimberley Process.

Daily Care of Your Diamonds

Diamonds may be the hardest substance known to man, but they can still get scratched and damage. Here are some tips on how you can make your diamond really sparkle:

  • Avoid contact with chlorine bleach, which can pit or discolour the mounting.
  • Avoid wearing your diamond while doing heavy work – diamonds are hard, but can still be chipped by a hard blow against the grain.
  • Diamonds can scratch each other, as well as other stones and metals, so keep them separate from your other jewellery to avoid damage.
  • To clean your diamonds, brush them gently with a clean toothbrush in a bowl, of warm, liquid detergent suds. Then rinse through a wire strainer before patting dry with a soft, lint-free cloth.

Ask Us Anything

We’re always happy to answer questions you have about your diamonds, jewellery and watches. For advice on care, cleaning, valuation, servicing and repairs use our showroom locator to contact your nearest showroom or make an appointment.

Alternatively, contact our client support team.

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