I found this interesting article about gemstone durability from GIA 4Cs blog and thought to share it with you, gemstones lover!
1. Gemstone Hardness = resistance to scratches and abrasions
A gemstone’s hardness is a good indicator of how well it will resist scratches and abrasions. The Mohs scale ranks gems on a relative scale based on their scratch hardness, so although corundum (ruby or sapphire) is a 9, a diamond at 10 is many times harder. Only a diamond can scratch a diamond. Corundum can scratch itself, topaz (8), quartz (7), and anything softer. Topaz can scratch itself, quartz (7), and anything lower on the scale.
2. Gemstone Toughness = resistance to breaking and chipping
The way the atoms of a gem bond together and the strength of these bonds determine a gemstone’s toughness, or how well a gemstone resists breaking and chipping.
3. Gemstone Stability = resistance to chemicals, heat, humidity and light
Stability refers to how well a gemstone can withstand exposure to chemicals, light, and changes in temperature or humidity. Some key causes of gemstone damage include:
Extreme Temperature Changes
Diamonds are very stable, but sudden and extreme changes in temperature can create fractures and cleavages or cause existing ones to spread. Thermal shock is the term to describe this and results from a sudden change from very warm to very cold temperatures. This sudden temperature change will damage gems such as apatite, iolite, kunzite, opal, and tanzanite.
Other gemstones are susceptible the humidity of their surroundings. Opals can lose moisture in low humidity or when exposed to heat causing them to crack or craze. Vaults and safes are usually very low in humidity and will dry out opals. On the flip side, long exposure to water can damage some gems, such amber, azurite and malachite.
Prolonged Exposure to Heat and Light
Gemstones like citrine, amethyst, kunzite, and topaz can fade or change color from prolonged exposure to light. Long-term exposure to heat and light can damage most organic gems, like amber, pearls, jet, coral and ivory.
Exposure to Chemicals and other Materials
Chlorine, and even perfume and makeup can damage or discolor delicate and porous gems like pearls. Chlorine can also damage gold mountings. Ammonia will damage the polish on many softer gems such as malachite, turquoise and coral. Wearing your fine jewelry while cooking can put it at risk of exposure to heat or spattering oils. Turquoise can easily absorb different liquids, including oils, which will discolor or degrade the gem.
Gemstones have been revered for their beauty and durability for thousands of years. Properly cared for, they become the treasured heirlooms that survive generations. So that you can best care for your gemstones, know their properties and qualities and keep your fine jewelry in good repair.
Read the complete article and more tips at: More than the Mohs Scale – Understanding What Makes a Gem Durable