Mineral materials are inorganic materials with ionic and covalent bonds. They are characterized by their mechanical and thermal resistance, some even having a refractory character, and are electrical insulators. Rocks, crystals, ceramics or glass are examples of mineral materials.


Ruby, like sapphire, belongs to the group of corundum. It is widely used in watchmaking for its technical characteristics which allow the reduction of friction at the level of pivoting. It is also sometimes used for aesthetic reasons on the setting of a case for example.


Diamond is crystallised carbon. It is the hardest of all materials. Unlike many other materials, its hardness does not make it particularly breakable. It is also precious and is regularly used in jewellery watches.


Sapphire, like ruby, belongs to the group of corundum. Since the middle of the 20th century, its synthetic and transparent version is regularly used as a crystal. Its natural version, usually blue but also other colours, is used in jewellery watches.


Silica, or silicon dioxide, is the main component of sand and, de facto, glass. In watchmaking, silica is used for sand-blasting operations, as well as in various forms of abrasives for the manufacturing or decoration of a component. In the form of glass, it is still occasionally used for watch crystals, although it is gradually being replaced by sapphire crystals.


Emerald is a green coloured stone which belongs to the beryllium group. It is a stone that often comes from Colombia. It is known for its noble inclusions called the garden of the stone.


The four precious stones are diamond, ruby, sapphire and emerald. Other so-called semi-precious stones can, however, according to some gemologists, also fall into this category. The separation between precious and semi-precious stones is sometimes questioned by some gemologists.