From the ancient Greek adamas (unbreakable), the diamond is the hardest mineral that exists. The purest gems are characterized by the absence of colour but there are other varieties: yellow, blue, and pink. From time immemorial, thanks to its brilliance, it is the most important and famous amongst gems.
The ruby belongs to the corundum family and is the rarest of all the gemstones used in jewellery. Its typical red colour is due to the chromium; moreover this main feature remains stable under heating. The main deposits are located in the following countries: Burma (Myanmar) with gemstones known as "pigeon blood"; Thailand (Siam) with gemstones with a purplish-brown colour; and Sri Lanka (Ceylon) with gemstones with a pinkish or violet-purplish colour.
The sapphire belongs to the corundum family and has magmatic origin. The blue colour is due to iron and titanium, but, unlike the ruby, its colour changes under heating. Its main deposits are in the following locations: in Kashmir where the gemstones are characterized by their wonderful blue-light blue colour and sheer transparency; in Burma (Myanmar), Thailand (Siam), and Cambodia where the deposits are very productive and the gemstones have a very typical intense colour, while the gems from the Sri Lanka (Ceylon) deposits are called "Our Lady's mantle" and are characterized by the beautiful, intense and uniform blue colour.
Emerald is the very finest variety of the beryl family. Its main features are: the non-uniformity in colour and the rare clarity of gemstones. Moreover, the inclusions inside the gems make them very fragile. The main deposits are in Brazil, Africa, and Colombia.
Aquamarine belongs to the family of beryl and is characterized by a typical green-light blue (aqua) colour. It is considered the "fifth stone" because, after the precious stones, it is the most valuable one.
Morganite belongs to the family of beryls and its main feature is the typical peach blossom pink colour. The quality of gemstones varies depending on the colour shades. Usually morganite is a very clear gem and with no inclusions.
Rubellite belongs to the family of tourmalines and its main feature is a deep red colour. The inclusions inside the gems emphasize their colour, giving them a velvety appearance.
Indicolite belongs to the family of tourmalines and its main feature is a typical greenish- or greyish-blue colour. The main deposits are in Kashmir and in Brazil, but the most valuable gemstone come from the state of Paraiba.
Tanzanite belongs to the family of zoisites and its name comes from the discovery of the first deposits of this gemstone in 1967 in Tanzania. Its original colour is light blue-violet, but most of the gemstone on the market is obtained through heating process that provides it with a marvellous purplish-blue colour, similar to some sapphire gems from Sri-Lanka.
Amethyst is the very finest variety of the quartz family; its colours have a wide chromatic range, but the most famous variety known on the market has the typical purple colour. Amethyst is heat sensitive: through the heat the gemstones take on a nice golden colour and are sold as "Madeira Topaz".
Kunzite is a variety of spodumene with a very intense pinkish-violet colour. The gemstones tend to fade if they are exposed to UV rays.
Topaz has magmatic origin and its gemstones have a lively vitreous lustre and a great brightness. The different inclusions inside the gems provide them with different colours from blue to brown, golden yellow and red.
Turquoise is one of the few stones that has a millenary tradition; in ancient Egypt, more than 6000 years ago, the Pharaohs used it as an ornament. Its typical colour is a delicate light blue and it is not transparent.
The tsavorite is a mineral belonging to the garnet family. From these stones can be obtained, red, yellow, orange and green gems of notable value. The tsavorite has a glassy shine, and thanks to its satisfying hardness and dispersion, it presents a lively appearance. The term tsavorite is used for the green stone and derived from the name of the park situated at the borders between Kenya and Tanzania where the mineral was discovered for the first time.
Coral is a marine organism of great beauty, whose name comes from the Latin "corallium" of uncertain etymology, which could mean "hard skeleton" or "mermaid" because of the human appearance of some of its branches. Coral consists of the skeleton of small polyps that grow next to each other, building extensive coral atolls and barrier reefs. In jewellery varieties of "precious" coral are used (Corallium rubrum), whose colour varies from dark red (oxblood) to dark brown and pale pink (angel skin). Coral is very sensitive to acids.