When picking out a gemstone for a particular piece of jewelry, the hardness of the stone is one of the things that must be considered. The “Mohs” scale is the grading system for determining a gem’s hardness. This is a “relative” scale, meaning that if a diamond can scratch a Ruby but the Ruby won’t scratch the diamond, the diamond is harder. Hardness is rated on a 1 to 10 scale, with 10 being the hardest (diamond). See the list below that shows the hardness of various gems.
Why Gemstone Hardness Matters
If you found a gemstone you liked and wanted to mount it in a ring setting but the hardness was only a 5, chances are it could get scratched or chipped easily as you perform everyday tasks. On the other hand, earrings or necklaces are subject to less wear and tear, since they aren’t in continuous or sudden contact with other objects.
For rings or perhaps bracelets, you might consider a harder gem that will withstand the intense wear of daily use. Gemstones that are a 6.5 to 10 on the Mohs scale are much more durable in ring settings. A gemstone that rates 5 in hardness works fine for a necklace or a pair of earrings because there is less chance of it being damaged.
Another consideration is picking a gem material that is not too difficult to cut. Materials that are under 5 or over 9.5 in hardness are very time-consuming to cut, and it takes special equipment to cut a gem that is a 10 in hardness.
Natural Gemstone Hardness
Benitoite 6 – 6.5
Beryl 7.5 – 8
Feldspar 6 – 6.5
Opal 5 – 6.5
Peridot 6.5 – 7
Tourmaline* 7 – 7.5
Man-Made / Synthetic Gemstone Hardness
Cubic Zirconia 8.25
Green Amethyst – Rosebud Cut