Gemstone Hardness, Toughness & Durability

Hardness is a physical property of gemstones. Hardness is the resistance or surface strength of the stone against scratches. Hardness defines the durability of the gemstone, the ability to retain its surface finish and polish.

Moh’s scale is used to measure the hardness of a stone. It is a relative and not an absolute scale and created to compare the hardness of gemstones. This scale rates hardness of minerals on a scale of 1 to 10. Position 10 is allotted to Diamond as it is the hardest mineral on Earth.

Moh’s scale is a qualitative scale characterizing the scratch resistance of the mineral. Scratch resistance is the ability of harder material to scratch softer material. This scratch test can be destructive. Thus, only rough/unpolished stones are tested through this method. Note:Only a Diamond can scratch a Diamond.

Hardness is often confused with toughness, but Toughness is different property related to the internal strength of a gemstone. Toughness is the resistance against breakage i.e. how easily a gemstone can be broken into two or more pieces. A hard stone may be not be essentially tough and vice-a-versa. For example, Diamond is the hardest stone but not the toughest while Jade is toughest but not the hardest stone.

Gemstones with less hardness are not preferred to be used in jewellery as they lose their luster and finish in very short span. Sapphire, Ruby, Topaz and Diamond are the most durable stones due to high hardness and thus are widely used in jewellery.