Mohs Scale: the most well know scale to measures relative hardness of minerals is know as the Mohs scales. Examples include:
- Diamond – 10
- Ruby & Sapphire – 9
- Topaz – 8
- Emerald – 7.5
- Feldspar – 6
- Apatite – 5
- Fluorite – 4
- Calcite – 3
- gypsum – 2
- Talc – 1