Jewel Talk


Many buy their gemstones without knowing whether they are heated or not. Perhaps, they have not heard that there is a difference between these coloured gemstones.

Did you know that about 95% of coloured gemstones goes through a process of heating to enhance its colour and clarity? Is it acceptable? Yes, it is! Also, it is commonly used in the trade. Heat treatment is as old as its trade and only in the 1970s, Thailand started heating Sri Lankan Sapphires in large batches.

Why do they need to heat treat these gemstones that are created by mother nature? Many roughs may be pre-maturely mined and the treatment aims to finish the process that mother nature didn’t get to complete. Coloured gemstones are more attractive when the colours are more saturated and vibrant.

When a gemstone is unheated, this means the colours are already beautiful when mined and no such treatment is needed. These make up less than 5% of total mined and are indeed rare. Visually, only a gemmologist can tell the difference between a heated and unheated gemstone. When buying an unheated gemstone, do make sure you ask for a certificate to proof that.

Value wise, an unheated piece can cost more than a heated one. If your priority is for investment, then perhaps acquire a piece that is unheated. However, if you are just wanting to own a nice piece that is more affordable, there are many choices of one with good clarity and colour within the heated category.

In summary, one should not just look at this treatment as the sole criteria when buying. There are many other factors you should also take into considerations when buying such as inclusions, colour zoning, evenness of fire and etc.

If you would like to learn more about “Heated vs Unheated Gemstones”, please join our webinar.