Moh's scale

We learned more about the properties of gemstones today. Using the MOh's scale gems are given a number that indicates how hard there are. Rubies and Sapphires are 9 on the scale.This determines how gems are set into jewellery. You cannot use Kiyanite which is 4 on the MOH's scale to set in a ring. The stone would not last long. It is safer to set it into a pendant.One must take note that this scale gives only an order of relative hardness. For example Diamond is 10 on the scale and Corundum is 9 on the scale but diamond is actually 140 times harder than corundum

Moh's scale of hardeness
1 - Talc
2 - Gypsum
3 - Calcite
4 - Fluorite
5 - Apatite
6 - Felspar
7 - Quartz
8 - Topaz
9 - Corundum
10 - Diamond