Synthetic does not mean plastic

The word gem is used for all stones of natural origin, i.e. stones formed naturally thanks to the presence of precise chemical elements in a suitable pressure and temperature environment. Gemology is the study of gemstones.

Synthetic stones, on the other hand, are man-made materials produced in laboratories or factories.

It is therefore important to note that synthetic stones are carbon copies of their natural counterparts. For example, synthetic sapphire is structurally identical to natural sapphire. As a result, they have the same optical, chemical and physical properties.

Artificial materials, on the other hand, are man-made and have no natural equivalent. For example, plastics and polystyrene are artificial.

Its origin

The first difference to bear in mind, of course, is that one is man-made, while the other is mined.

The presence of inclusions

The other notable difference, which enables gemologists to appraise a stone, concerns the inclusions (impurities) that can be found in these stones.

The natural environment can leave room for crystallization defects. These can be a variety of inclusions. These inclusions testify to the gem’s natural formation.

The synthetic environment can also give way to certain inclusions, this time characteristic of the synthesis processes and treatments required to create these stones in the laboratory.

Natural sapphire and synthetic sapphire

Let’s take the example of a natural sapphire, as well as a synthetic sapphire manufactured by the Verneuil process (flame fusion synthesis).

The distribution of color in both stones is due to the presence of iron and titanium.

Unlike natural sapphire, their synthetic counterparts are created with a rotational movement. This rotation is noticeable when the material crystallizes.

Thus, we can see the presence of “curved growth zones” for synthetic crystals (top photo), and “straight growth zones” or “chevrons” (angles) for natural ones (bottom photo).

Please note that there are other synthetic processes for sapphires, which may have “straight growth zones”.

Thus, a sapphire can be described as synthetic when curved zones are observed; but a synthetic sapphire cannot be described as natural solely on the basis of straight or herringbone zones.

Natural emerald and synthetic emerald

There are other differences between natural stone and its synthetic counterpart. Take emeralds, for example.

A natural emerald may have inclusions of small crystals of other minerals, such as chromite (left photo).

Synthetic emeralds, on the other hand, are the result of a hydrothermal dissolution crystallization process, and may feature “phenacite nails”: small, elongated phenacite crystals characteristic of the hydrothermal emerald manufacturing process (right photo).

It’s not uncommon to find a stone with no inclusions at all. In this case, there’s no way for the naked eye to tell the difference between natural and synthetic stone.

It’s more convenient to call in a gemological laboratory to carry out more detailed analyses to determine a gem’s naturalness.

The two materials are so similar that it is necessary to use spectrometric analysis machines to identify the proportions of trace chemical elements, which in turn determine whether the stone is natural or synthetic.

This analysis is often combined with other advanced analyses to establish a laboratory certificate of authenticity.