Hardness and toughness standards of gemstones
Gemstones require different cleaning methods based on their hardness and toughness. The measure of a mineral’s hardness and it’s resistance to scratching was invented by a mineralogist named Friedrich Mo. He invented a scale that ranges from talc (number 1) being the softest, to diamonds (number 10) being the hardest substance. The toughness of a gemstone is the resistance to breakage. The combination of the toughness and hardness of a stone largely defines its durability.
To clean PEARLS:
A pearl’s toughness is poor and on Moh’s hardness scale it receives a 2 ½ - 4. This means you should never steam or boil your pearls to clean them. You should never us a soapy brush to clean them either. The only way to safely clean your pearls is to use an untreated cloth.
