Aluminium in precious stones

The colour, the brilliance, the reflections, the strength and the heat resistance – these are the properties which make precious stones so special and, of course, so incredibly beautiful.

Considered scientifically, every precious stone is a compound of minerals, that is a chemical composition. Amazingly, one of the components contained in many precious metals is aluminium. The portion of the light metal varies from one stone to the next. It is most abundant in rubies and sapphires. The chemical formula of these precious stones is: Al2O2. This means that they are made up of pure aluminium oxides with coloured additives. For example, the characteristic colour of a ruby (a raw stone can be seen on the right) is red. Both rubies and sapphires belong to the corundum family and have a hardness of 9. They are thus almost as hard as diamonds.

Aluminium oxides absorb heat easily. Rubies and sapphires can therefore be placed in the sun and have hot water poured over them without any damage. The characteristic property of aluminium of absorbing heat and conducting energy is therefore a special feature of the "aluminium gems". However, care is required with rubies – too much sun can cause their colours to pale.

Aluminium is a versatile material. The spectrum of its manifestations is large: from simple to complex, from reasonably priced to very valuable.


Overview