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A Buying Guide to Coloured Gemstones

A Buying Guide to Coloured Gemstones
- An article from Gem Discovery Moments E-newsletter Dec 2018 issue
(by The Gem Museum & Far East Gems & Jewellery)

When it comes to buying diamonds, people are familiar to use the 4Cs (Carat weight, Cut, Colour, Clarity) as their shopping guide.

But what about coloured gemstones like rubies, sapphires, emeralds, aquamarine and more? How do we choose a coloured gemstone and what factors determine its price? 

First of all, gemstones are always chosen for their beauty when we buy them, whether diamonds or other type of coloured gemstones.  While beauty is in the eye of the beholder, there are standard attributes that we can look out for to determine the beauty and worth of a gem. 

Just as white (or rather colourless) diamonds are chosen base on the 4Cs attributes, we can also use 4Cs as our buying guide for coloured gemstones. Let's talk about them and other tips here:

Color
For coloured gemstones, the more vivid, intense, stronger or fancier the colour, it will be considered as more beautiful and hence the price will be higher per carat. For example, if based on colour alone, a pale light blue colour sapphire compared to a royal blue sapphire will be more affordable. Lucky you, people who like pale, pastel colour for gems!  





Left: 1.97 ct Sapphire S$350/ct  
Right: 1.34 ct Royal Blue Sapphire S$4,500/ct



Clarity
Similar to diamonds, the greater the clarity of coloured gemstones, the more beautiful and valuable it is. For coloured gemstones, it is common to have inclusions in them and generally accepted if they are not as visible to the naked eye, which is called eye-clean. Especially with the darker coloured gemstones, the inclusions are usually visible only under the close examination of a loupe. 

Cut & Carat 
The shape of the gemstone does not determine its value though some shapes maybe more popular than others. But the cut of the gemstone does, because a well-cut gemstone is more beautiful, reflecting more light and fire, making it more shiny. For coloured gemstones, the price also jumps as the carat weight goes beyond 1 carat, and another jump beyond 2 carats, similar to diamond pricing. 

Heat or no Heat
When you shop for coloured gemstones, some of them are labelled as 'No Heat'. It means that the gemstone has not undergone heat treatment to enhance its colour. Heat treatment is an industry practice to enhance the colour of the gemstones and the result is a permanent colour change and thus an acceptable industry practice. This makes beautiful colour gemstones available to more people at prices within their reach.  The colour is naturally beautiful and thus, they are rare and priced higher per carat. 


If you are interested to learn more, you can join the free Gem Discovery Masterclass brought to you by The Gem Museum. Class information is available HERE

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