All of us remember that in school it was fundamental to learn the various phases of biological classification: kingdom, phylum, class, order, family, genus and species. All animals, vegetables… and minerals fit into this order. Chemical composition and crystal structure distinguish a particular mineral. These two characteristics determine the species, which is labelled with a name (diamond, gemstone..). A minor variation in either of these properties results in formation of a different mineralogical species with a distinct name. Species with similar characteristics constitute a group. Stones belonging to the same mineral species are often varied with respect to what is known as their optical characteristics. These include colour, transparency and optical phenomena. Differences in these factors determine a crystal’s variety. For example, rubies and sapphires are varieties of corundum. Rubies are characterised by their red colour, while sapphires are blue.

Synthetic and imitation stones
Based on their origin, stones can be classified into the following types.

Synthetic: laboratory reproductions of stones already existing in nature, having the same physical, optical and chemical characteristics as their natural counterparts (specific weight, refraction index, etc.).
Artificial: stones that do not exist in nature.
Natural: further subdivided into organic (coral, amber, ivory, pearls, etc.) and inorganic.

The term “imitation” is used to describe any substance that has physical aspects similar to a natural stone. Since the times of the ancient Egyptians, imitations were used to copy coral, lapis lazuli and turquoise. They can be made from natural substances or substances created by man (glass and plastic). Plastic is generally used to imitate organic substances such as coral, pearls, amber, etc., while glass is used to imitate all other stones.

In the world of jewellery, the pureness and authenticity of natural stones has always been highly valued, while synthetic and artificial versions have been rejected. Today, the jewellery industry is in danger of falling into temptation, seduced by the extreme precision of synthetic stones and their ease of introduction into production chains, as well as by their low cost.

The Rajola policy has always demonstrated a for natural stones over any type of imitation.
Although the costs and difficulties involved in finding natural stones constitute a considerable impediment, when we think of a jewel we imagine it to be an object that is precious for its intrinsic beauty, its artisan value and even its value over time – a quality that synthetic and artificial stones do not have! Every natural stone is unique. While this may be considered a limitation photographic credits.