The characteristics of gems

Gemstone treatments:

Nowadays, a major part of gemstones is treated. It results from the extrem rarity of unincluded nice colored stones.

That’s why the producers use to treat gems in many ways, even in unacceptable ways.

Here are the most used ways of treating.

HEATING : Also called Bâta Kumbalâ, this technic consists in heating a gem in view of improving its colour and clarity.

DEEP DIFFUSION TREATMENT : This technic consists in beryllium-like material depth diffusing in the stone. This is used to get totally different colours than the original stone, generally very rare in the nature (like the orange sapphires for exemple).

These two treatments are agreed on the gemstone market, but have to be registered on the stones certificates.

The two following treatments, however, are considered as a deceit by the negociants. Though, any indelicate producers don’t hesitate to use these technics. The greatest vigilance is appropriate when you buy a stone of a certain weight.

IRRADIATION : As its name indicates, this technic consists in irradiating a stone. The sole intention of this treatment is to improve the gems colour. Besides its set time limited effect, it represents an obvious danger for health.

FILLING : Any gems may presents cracks on their surface. These cracks are filled with various substances: oil, resin, or else high density glass. Not only do it hide the fragility of the stones but it improve their colour in a totally artificial way.

Synthetics and Imitations:

SYNTHETIC: Most of the time, unincluded gemstones are synthetics. Actually, in their natural state, the major part of gemstones, and especially precious stones as rubies and sapphires are, above all emeralds are included.
Such stones, unincluded, are extremely rare.
This is an important point you have to take into account when you decide to invest in a stone. Don’t hesitate to ask a certificate. It represents a real security for you


IMITATIONS : There are a lot of stones that are used to imitate any others of higher value. For example, the spinel is sometimes used as an imitation of ruby. Another decceit consists in making doublets or triplets which are an assembly of a natural stone with a synthetic one or an imitation.

Our Advice : Always ask for a certificate when you decide to invest in a high value stone.
You could be sure of its quality. You will know its origin and the treatments that it has eventually suffer.

At DIAMANT-GEMS you only find the highest-quality stones, almost all of which are certified.

Optical Phenomena :

Most of gemstones seem to play with light when they are exposed to a direct light source.

These phenomenon are due to the presence of different inclusions which cause any interferences when the light hits the stones.

The SILKY EFFECT is a reflective effect from the top of the stone due to the presence of needle like inclusions nests.

CHATOYANCY, also called ‘cat’s eye’, is due to reflections from numerous parallel cavities or fine fibrous inclusions regulary oriented in accordance with the symmetry of the crystal.

L'ASTERISM is similar to chatoyancy except when the cavities or fine-needle like inclusions are parallel to more than one crystal face. Then, a star-stone is produced when it is cut cabochon.

ADULARESCENCE, a commonly whitish or bluish sheen seen in the moonstone, is due to an intergrowth of feldspars in alternate layers.

L'AVENTURESCENCE is a scintillation of the stone due to light inferences caused by flat crystals of mica.

IRIDESCENCE, a sort of prismatic light, results of the refraction of the light on the different crystal layers.

La LABRADORESCENCE is a flash of vivid colours due to twinned feldspar crystals.

OPALESCENCE is the scatering of light by particles of matter in the path of the light, making a visible "beam" or "cloud" such as is caused by a ray of light illuminating particles of dust floating in the air of a room.

The PLAY OF COLOUR which is shown in precious opals results from the light diffraction due to the different layers of silicium in the opals.

The ALEXANDRITE EFFECT that is shown in Alexandrite or other stones results from the different way of natural and artificial light absorbing that any crystals have.