Amethyst - Hardness and toughness
Common substances like sand and dust are composed mostly of quartz, the mineral species that includes the purple variety amethyst. So, while amethyst is a great gemstone for use in jewelry, it should be treated with the proper care to prevent scratching and other damage.
Amethyst rates a 7 on the Mohs scale and has good toughness, so it is suitable for all jewelry types. This includes rings as long as the wearer understands the limits of its hardness.
A ranking of 7 on the Mohs scale means amethyst is a durable jewelry gem as long as proper precautions are followed to prevent scratching.
Abrupt temperature changes can cause amethyst to fracture. Some amethyst color can fade with prolonged exposure to intense light. Amethyst can also be damaged by hydrofluoric acid, ammonium fluoride, and alkaline solutions.
Amethyst can be safely cleaned with warm soapy water. Ultrasonic cleaners are usually safe except in the rare instances where a stone is dyed or treated by fracture filling. Steam cleaning is not recommended, and amethyst should not be subjected to heat.