How to identify the treated and untreated Sapphire gemstones

In gemstone market, it is very hard to find an untreated piece because of the lack of interest from the buyers. Untreated sapphire gemstone is often mistakenly referred to as natural. The treatment process has nothing to do with the origin of the gemstone in any way. Lapidary units create eloquent sapphire gemstones using elaborate treatments. 

Let us find the real differences between the two families. 

Untreated gemstone

The stone that has been developed from the ground and never cut or polished in any way in a lab is labelled as ‘natural’. When the natural stone is not subjected to any chemical or heat treatment, it qualifies as an untreated gemstone. 

Heat treatment, optical irradiation and chemical treatments are done on various gemstones to achieve brilliant colours, clarity and some times better refractive index. Sometimes, a treated natural gemstone is easier to cut and polish than the untreated ones due to better clarity and machining properties.

What happens in gemstone treatment process?

All stones available in the market are subjected to treatments in some form or the other. Heat treatment process changes the colour and clarity. It is during this process that additives and glue are added to fill cavities, fractures and cracks. 

How to identify a pure gemstone?

Gemstone buyers should know certain tell-tale signs to identify 100% pure and natural stones. Regardless of the tag, here are some of the signs you can check to verify the claim of authenticity.

1. Naked eye test 

A true natural stone will reflect light and exhibit lustre. There are many stones that have a dull, waxy and shiny surface. There are some with greasy and silky appearance. High quality stones will reveal rings, stepped granules, splinters and sometimes clear waves inside them. Any polarised chipping in the stone highlights its synthetic origin.

2. Hardness and clarity

Most gemstones have hardness close to diamond. They can’t be scratched or cracked easily. Artificial gemstones, bordering at being fake, are created in the lab and resemble glass. A gemstone from natural treated family will have pure clarity and no cracks. In case of fake artificially treated stones, you can clearly see speckles and minute cracks within the structure arising due to intense heat and pressure

3. Density 

Original stones even after heat treatment will retain their density. Synthetic stones that are subjected to heat treatment gain a few points and actual weigh heavier than the natural stones. This is how lapidary and stone collectors verify Blue sapphire gemstone.

4. Crystal layers

Most gemstones from the natural deposits have a parallel layer running inside the surface. This is what gives the stone its saturation and intensity. For warm coloured stones, look for brown tinge. Reject the stone if you see even the dullest shade of greyness.

The colouring dyes and reinforcing agents diffuse completely throughout the crystal structure uniformly. Some heat treatments produce dramatically altered gemstones that not only look brilliant but also compound the original hardness.

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