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Gemological Terms - Durability

There are dozens of different gemstone types that are very beautiful. But in order to be suitable for use in jewelry, they must be durable as well. A gemstone’s durability is measured by three different properties - toughness, hardness, and stability.

Toughness determines how resistant a gemstone is to chipping or breaking. It is measured on a scale from poor to exceptional.
Hardness is measured by the Mohs Scale, which assigns gem materials a number between 1 to 10. Friedrich Mohs developed the system in 1812 by testing which gems could scratch the others, and ranking them on this basis. However, the scale is relative rather than absolute: diamond (the mineral rated as a 10) is actually about four times harder than sapphire (9). Compared to talc (1), diamond is 1,500 times harder!
Stability determines how a gemstone reacts to heat, light, and chemicals. Certain stones are more likely to be damaged if exposed to extreme temperatures, and others can fade if they are exposed to sunlight for an extended period. Acidic materials can damage some gem materials, especially organics such as pearl.

A gemstone’s durability can also help determine what types of jewelry would suit it best. More fragile stones such as opal, tanzanite, and pearl are safest when set into earrings or necklaces. Extremely durable gems like diamond, ruby, and sapphire can safely be worn in rings or bracelets. Of course, with the proper care any gemstone can last for a lifetime no matter how it is set.