Gemstone Buying Guide

Buying an item of jewellery can be a daunting task. At Gems Jewellers our aim is to provide you with a simple approach to guide you through the necessary steps when you choose your gemstone. This guide defines essential characteristics of gemstone quality. By understanding these characteristics, you'll be able to gain an in-depth knowledge of our gemstone jewellery to help aid your decision on which gemstone you prefer.

The criteria used to assess the value of a gemstone are Colour, Clarity, Cut and Carat.


The highest quality gemstones stand out with the purity of their hue, the depth of tone, and the colour saturation. The best value is in colours that include "slight" traces of other colours, are not too light or dark, and have a lot of saturated colour. At Gems Jewellers we offer some of the highest-quality coloured gemstones available in the UK.

A significant number of gemstones undergo treatment to enhance their colour. The most common methods of treatment are heating; which is used for aquamarine, citrine, amethyst, sapphire, ruby and tanzanite gems.


Almost all gemstones, including the most highly prized available, contain inclusions. Flawless gemstones are extremely rare and highly sought after. Emeralds for example tend to have a higher rate of “acceptable” inclusions. Whereas, aquamarine, blue topaz, and citrine, have naturally fewer inclusions. When considering a coloured gemstone's clarity, you should measure your expectations against the standard for that variety of gemstone.

The best value is found in gems that have light to moderate inclusions, of which Gems Jewellers is a renowned stockist in the UK.  We work closely with gemmologists to constantly source the highest quality gemstones at a competitive and affordable price.


Gemstones are generally cut to maximise the beauty of their colour and retain the original weight. To recognise quality in the cut of a gemstone there are several points to consider: a good cut defines the gemstone's colour, reduces its apparent inclusions, and exhibits good overall symmetry and proportion.  In almost all cases, a well-cut gemstone is symmetrical and reflects light evenly across the surface, and the polish is smooth, without any nicks or scratches.

These are the characteristics that Gems Jewellers look for upon selecting the best gemstones that go into making our pieces.


The carat weight of a gemstone does not necessarily allow you to accurately visualise the size of the gemstone.
Different gemstones have different densities, so two gems that appear to be the same size may actually have very different weights.
For example, a ruby is denser than a diamond, so a 1 carat ruby will be physically smaller than a 1 carat diamond of the same size and shape.