When deciding what gemstone you want in your jewellery and how to care for those gemstones there is something to keep in mind...
…Moh’s Scale of Hardness.
Developed in 1822 by the German mineralogist Friedrich Moh, this scale is the most common method used in the jewellery industry to assess a gemstone’s hardness.
Hardness is a measure of how easily the surface of a gemstone or mineral can withstand abrasion which can be caused by wear and tear as well as scratching. The hardness of a gemstone is important when deciding what type of stone to choose i.e. a particularly soft or brittle stone is not suitable for every day wear. When storing jewellery, diamonds and harder gemstones should not be kept with softer gemstones or pearls etc. as they may scratch or damage them.
The scale itself is relative and ranks 10 easily obtainable minerals from 1 (softest) to 10 (hardest) and essentially a mineral will be able to scratch those with a lower number, but would be scratched by a higher number.
As Moh’s scale is not a linear scale it does not increase by equal increments; for instance a diamond, which scores 10, is 140 times more scratch resistant than corundum, which scores 9. A list of the representative minerals and their hardness follow:
1 – Talc – Fingernail scratches it easily
2 – Gypsum – Fingernail scratches it
3 – Calcite – Copper penny scratches it
4 – Fluorite – Steel knife scratches it easily
5 – Apatite – Steel knife scratches it
6 – Feldspar – Steel knife does not scratch it easily, but scratches glass
7 – Quartz – Hardest common mineral: it scratches steel and glass easily
8 – Topaz – Harder than any common mineral#
9 – Corundum – Scratches Topaz
10 – Diamond – Hardest of all minerals