Heated or unheated gemstones?
Some of you will face this question when buying a precious stone, since man has always heated stones to enhance the quality of color or transparency.
In fact, the heat treatment causes alterations in the physical and chemical structure of the gem and improves the color purity of gemstones.
This is an absolutely stable process and tolerated in the market for fine and precious stones. This is part of industry practice.
Heat treatment of corundum (rubies and sapphires) has been practiced for hundreds of years now.
Currently, almost all rubies and sapphires, the majority of products on the market are heat treated. The heat treatment of corundum has been used for centuries and that is why he is considered a common practice and even a traditional use.
In recent decades, following the invasion of “hot rocks” on the market (some 95% of corundum), some purists have been looking for stones thermally unaltered by the hand of man.
This is what we call more communemment stones “unheated”.
A ruby or sapphire unheated, with certificate of authenticity, will see its price increase more rapidly than the color is beautiful and the weight important.
In other hand, the fact that a sapphire or a ruby is “heated” should not be rejected.
There are beautiful stones heat treated, whose color has nothing to envy to a stone “unheated”.
Remember, one must first buy a stone after the emotion it gives you … and your budget!
However, heat treatment does not need to be mentioned on the certificate as some “newer” treatments will need to be.
These specific “new” treatments known as “diffused”, “bombing”, “colored oiling”, “filling resins” are resulting from new development techniques and should be mentioned on certificate.
As per Emeralds, due to their extreme fragility, they can’t be heated but the profession tolerate what we call “oiling”.
Oiling is intended to fill cavities or open cracks on the surface by the inclusions through a colorless oil.