You may have wondered why you find the Mohs' scale of hardness in the description of the gemstones. The hardness or the resistance to scratches determines the durability of the gemstone.
The German born mineralogist Friedrich Mohs (1773-1839), student of Abraham Werner, developed a scale that measures the scratch resistance from hard on soft minerals. The scale goes from 1 to 10, talc being the softest (1) and diamond being the hardest (10). With your fingernails, which have a hardness of 2.2, you may scratch talc.
As a consequence when cleaning your gemstones and jewelry you need to take into account their scratch resistance so as not to damage them.
Care about your porous gemstones. Do not spray cosmetics or perfume while wearing them, chemicals may damage them.
CLEANING GUIDE GEMSTONES
Mohs' hardness Ultrasonic** Soap*** Untreated cloth°
- Agate** 6.5 – 7.0 No Cold water Yes
- Amazonite 6.0 – 6.5 No Yes Yes
- Amethyst 7.0 Normally yes Yes Yes
- Aquamarine 7.5 – 8.0 Normally yes Yes Yes
- Carnelian 7.0 Normally yes Yes Yes
- Citrine 7.0 Normally yes Yes Yes
- Coral 3.5 – 4.0 No No soap Yes
- Diamond 10.0 Yes Yes Yes
- Emerald 7.5 - 8.0 No (fracture risk) Yes Yes
- Fluorite 4.0 No Yes Yes
- Garnet 7.0 – 7.5 Normally yes Yes Yes
- Howlite 3.0 – 3.5 No Yes Yes
- Jade, jadeite 6.5 – 7.0 Yes Yes Yes
- Jade, nephrite 6.0 – 6.5 Yes Yes Yes
- Kyanite 4.0 – 7.5 No Yes Yes
- Labradorite 6.0 – 6.5 No Yes Yes
- Lapis-lazuli 5.0 – 6.0 No Yes Yes
- Malachite 3.5 - 4.0 No Yes Yes
- Moonstone 6.0 – 6.5 No Yes Yes
- New jade 2.5 – 5.5 No Yes Yes
- Opal 5.0 – 6.5 No Yes Yes
SEE - part 2