The International Gem Society defines a gem as “a mineral that has been chosen for its beauty and durability, then cut and polished for human adornment.”
Most gems are minerals. Others, like pearls or amber, are created from living organisms. Generally gems are of a color that resembles other natural elements we consider beautiful or valuable. Emeralds resemble the natural green of plant life, sapphires are the color of the sky and rubies are a rich blood-red. There are variations in color in all of these gems, of course, and in diamonds, but those are the colors most normally associated with them. Diamonds can come in colors as well, with pink and canary diamonds being highly valued variants.
Most gems are solid and enduring, even though pearls can be easily damaged, as can opals and moonstones. Generally a gemstone has to be durable enough to wear as adornment, but others, while too soft to wear, are valued by collectors. Pearls can eventually disintegrate, even if all you do is wipe dust off them. And if you spray hairspray or perfume on them, this can also ruin your pearls.
Opals are highly valued for their beauty and fire and make exquisite jewelry, but are extraordinarily susceptible to damage. They can shatter easily if dropped. And there’s a story of a woman who wore an opal brooch to a holiday party. When she left the warmth of the party to leave and the brooch experienced the sudden drop in temperature, it shattered, just like a glass that’s been heated and then cooled too quickly.
