Things To Look Out For When Buying Coloured Gemstones

Wednesday, 3rd May 2017

Before viewing prospective gemstones, think about your reasons for potentially purchasing one, as this could inform your choices:

Are you purchasing a gemstone to mount into a piece of jewellery?

  • If you are thinking of setting a stone into jewellery, bear in mind ‘calibrated’ sizes that are typically set into jewellery – if you are interested in a uniquely shaped or sized stone, bear in mind that a jeweller may have to hand craft a special mount to fit, bringing costs up.
  • Think about opting for stones higher up on the MOHS hardness scale, such as diamond, corundum and topaz in order to maximise suitability for setting into jewellery.

Are you purchasing a gemstone for educational reasons?

  • A group lot will allow you to examine a variety of different inclusions, colour zoning, and gemstone formations

Are you a gemstone collector?

  • Look for unusual pieces that would fit in the collection, for example unusual colours, inclusions and shapes may draw your attention.

Always look with a loupe!

It is worth viewing any gemstone under magnification, this is the best way of getting a real idea of any damage the stone has, and a look at any inclusions and features that may be inside the gemstone.


Colour is an important aspect to gemstone collecting, the saturation, vividness and correctness of colour is often the first thing we notice when spotting a gemstone.

Assess the colour of the gemstone in natural light, and if possible, under a daylight lamp. Examine the stone from various side as certain optical properties can make the appearance of the stone change when held through different angles.

Look for any optical features, such as play of colour, adularescence, ‘star’ and colour banding.


Decide on the state of the stone you are searching for. For collectors, rough crystals can be even more mesmerising than cut stones, offering clues about the formation and identity of the gemstone.

However if you opt for a cut stone, do you have any preference of shape? Would you rather have a faceted stone, a cabochon, or a carving?

Pay mind to how the cut has made the best of the natural crystal, for example stones with a deeper pavilion are typically cut like this to maximise the natural colour, rectangular cuts are more often cut from more tabular shape crystals.


It is worth considering the condition of any stone viewed. Whilst gemstones can be re-polished for light scratches and nicks, not much can be done to revive a stone with cracks and/or surface reaching fractures.

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