Enhancing Gemstones. Are They Still Natural?

How do you feel if I told you that 90% of the worlds sapphires are heat treated and so is nearly every ruby that you will ever see and that a good deal of the emeralds that you might buy are oiled and that you can safely assume that the topaz you are wearing has been heat treated or, and you wouldn’t think this, irradiated! Your pearls are probably dyed or bleached with chlorine or hydrogen peroxide, your beautiful citrine would not look that lovely colour without heat treatment and then tanzanite starts off its life as a dirty yellow brown crystal and turns into Cinderella after massive heat treatment. Every tanzanite that you are likely to see will have been heat treated. Well it’s true!

What I am going to tell you might make you think differently about that lovely piece of gemstone jewellery that you love to wear, but you’ll still be happy to wear it.

Firstly, before we jump to any conclusions and think that enhancing natural stones such as rubies and sapphires is a terrible thing to do, or somehow cheating, we should think about what natural stones look like when they are found or mined. In most cases they look like lumps of coal or dirty rock, or dull glass. Most of the time you would sweep them out of your hut without a care in the world.

The first alterations that everybody seems to forget about but are perfectly content with is shape enhancement or cutting of the stone. This is a very time consuming process where great skills are used to cut off most of the material from the natural stone. In many cases most of the material is rubbish and is thrown away. Then there comes polishing and faceting which is a part of the cutting process after the shape has been improved.

After that many more enhancements are carried out: bleaching, coating such as lacquering, dyeing, filling of internal cracks and holes, irradiation, heating, laser treatment, oil or resin infusion and many others.

Why are gemstones enhanced?

Well, obviously in order to improve their selling ability and their overall appearance.
Some, if not most, natural stones have what we call inclusions. These are imperfections inside the gem. They may be cracks, holes or foreign objects which cause cloudiness or just odd reflections.

How are gemstones enhanced?

In order to get rid of these imperfections sometimes holes are drilled into the stone and the imperfection is removed or perhaps a filler substance such as oil, wax, epoxy resin or other substance is placed inside the gemstone to fill the void.

A good example is the wonderful gemstone emerald. Emeralds may have internal fractures which change the way the light enters and exits the stone which alters its clarity and beauty. If the emerald is immersed in or coated with a substance such as an oil having the same refractive quality as the natural stone then the gemstone can achieve a step nearer to perfection.


Sometimes other methods are used to get rid of these inclusions. Heat treatment is often used for this purpose. Once a stone is heated to a certain temperature the inclusion may actually disappear forever. You probably wouldn’t think that this is a bad thing would you. When the stone is heated sometime these inclusions will dissolve and hence the stone will be improved.

Heat treatment is the most common form of enhancement done to gemstones and the main reason it is done is to improve the colour.

Sometimes a gem will change its colour just by low heat from a cigarette lighter or spirit lamp, but other times it takes enormous heat which takes the stone to almost melting point.

Sometimes this alone is enough to change the colour of the stone permanently but laboratory technicians in this field also heat these gemstones in the presence of other substances such as chromium oxide powder which will coat the surface and change the color.

Perhaps the wildest sounding treatment is irradiation which is commonly done to many gemstones. Topaz starts life off as a clear crystal and by irradiation it turns brown and then heat treatment turns it blue. The amount of this treatment determines whether it becomes a Swiss Blue or a London Blue or a Sky Blue. Is there any danger to humans? Well, there is some concern and a lot of debate about this.

These treatments are done to natural occurring gemstones. These are not man-made stones. That is another story again.

Some of these treatments have been done to gemstones for hundreds and hundreds of years. So even though your gemstones has been cut up, drilled and filled, irradiated and heated it is still natural. Funny isn’t it as this is hardly what we would consider a natural product when we think of most items that we buy.