When it comes to precious and semi-precious stones, sooner or later you will encounter the hardness scale developed by Friedrich Mohs – a German-Austrian mineralogist who, as it happens, established this classification—which is still in use today—during his professorship in Graz (starting in 1812).
At Feichtinger – with our headquarters in Graz – we are of course particularly pleased about this…
Mohs hardness 8 to 10 are for precious stones, 1 to 7 are for semi-precious stones
The hardness test is based on the principle that harder materials can scratch softer ones. Consequently, Mohs ranked minerals according to their hardness on a scale from 1 (soft) to 10 (hard). The degree of hardness of minerals is determined by their internal structure, the crystal lattice, the strength of which increases with higher Mohs hardness.
This scale also includes a
distinction between precious and semi-precious stones:
The former have a hardness of at least 8, while semi-precious stones are below that, i.e., between 1 and 7. That the proverbially hard diamond, the king of all precious stones, leads the list with a 10 is, of course, a matter of honor.
