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Why choose an unheated sapphire?

by Julie MIALET 04 Mar 2024

Sapphires, which are the third hardest mineral on the Mohs scale of hardness, are part of the corundum family.

Sapphires exist in different colors, the best known of them being blue, pink, yellow and orange….

Natural sapphires, also known as "untreated sapphires" are not necessarily "unheated", because "unheated" and "untreated" should not be confused!
By “natural” or “untreated”, we are talking about a sapphire that has not undergone any treatment….

But what is the treatment of a sapphire?

Some low-quality sapphires are treated to artificially improve their color: Treatments by irradiation, by laser, by dye, by surface diffusion, by filling or by any other laboratory method modifying their appearance, their color or their purity.
This type of treatment must be announced to the customer and must appear on the invoice.
Stones that have undergone such treatment are no longer considered natural.

But what is an unheated sapphire?

Heated sapphire is sapphire that has undergone heat treatment at temperatures of between 800 and 1,300 degrees (without the addition of heavy elements). At these temperatures, the inclusions dissipate in the sapphire, which becomes purer. The colour also intensifies and becomes more uniform.

As only rare sapphires are naturally pure and coloured at the same time, heating is considered a traditional and necessary embellishment technique that does not need to be specified on the invoice.

Why opt for an unheated sapphire?

As you will have realised, only rare unheated sapphires are naturally pure and coloured at the same time. Nearly 95% of sapphires on the market are "heated". This explains why "unheated" sapphires are extremely fashionable and highly sought-after.

Their colour and inclusions are natural and have not been altered by human hands. Unheated sapphires have natural inclusions such as butterfly wings, fine rutile needles, zoning and colour bands...

The prices of unheated sapphires vary, with the most expensive being the blue colour and the orange colour known as "Padparadsha", followed by pink, yellow and violet sapphires. The most sought-after origins are Kashmir, Burma/Myanmar (both names are currently in common use) and Ceylon, not forgetting Madagascar.

As unheated sapphires fetch higher prices, it is important that they are accompanied by a laboratory certificate specifying their nature at the time of purchase. Pierres de Julie specialises in sapphires, particularly unheated coloured sapphires.


All stones sold by Pierres de Julie are delivered with a laboratory certificate (LFG or Gem Paris)


If you are interested in sapphire, do not hesitate to discover what Les Pierres de Julie offers in store…

We are also available for any free expertise of your sapphire jewelry, for this you can send an email with your photos to

Whether you're interested in buying a piece of jewellery or a stone, a free jewelry appraisal or jewelry resale, Pierres de Julie welcomes you to its Parisian boutique in the Village Suisse, a stone's throw from the Ecole Militaire and the Esplanade des Invalides.

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