Metal Education and Guidance
The metals most often used in jewelry—gold, platinum, and silver—are called the precious metals, and they can be used alone or to complement the gems in a piece. Precious metals are expensive because they’re rare and difficult to extract from the earth.
Gold is a bright and sunny yellow. Platinum and silver are both considered white metals, even though platinum’s rich gray-white looks quite different from silver’s gleaming white.
One of the things people admire most about precious metals is their luster, or the way they reflect light.
Gold’s beautiful luster is what attracted people to it in the first place. It creates a rich background for the sparkle of beautiful gems. Platinum, too, glimmers alluringly in the light, a perfect complement to diamonds, pearls, and colored stones. Polished platinum’s luster can change over time, becoming softer and richer and achieving a subtle, enchanting glow called patina.
Workability, Durability, and Metal Memory
Most jewelry metals are workable, which means jewelry makers can fashion them into almost any shape, and they retain that shape.
Gold, silver, and platinum are also durable, meaning they’re strong and longwearing. They’re resistant to impact, and also resist corrosion, meaning they stand up well when they’re exposed to chemicals in the environment.
These precious metals also have “metal memory,” which means they tend to return toward their previous shape. Of the three precious metals, platinum has the least metal memory. Once platinum is bent, it tends to stay in position. This lack of metal memory means that platinum has superior holding power. This is the reason it is often used for prongs to hold gemstones.
Alloying gold increases its strength and hardness, and reduces its cost. Increasing the percentages of the other metals in gold alloys can result in customized colors. Varying amounts of copper can give gold a rose or even reddish color. Increasing the silver in a gold alloy can give it a green color, and nickel and palladium can whiten it.
In the US and most other countries, people use the term karat to state gold’s fineness, which is based on parts out of 24. This means that pure gold is 24 parts gold—or 24-karat gold. Gold that’s 75 percent pure—18 parts gold and six parts an alloying metal or metals—is 18-karat gold. Fourteen-karat gold is 14 parts gold and 10 parts another metal or metals. “K” is the abbreviation for karat, so you’ll often see gold jewelry stamped 14K or 18K. Don’t confuse “karat” with the term “carat,” a measure of gem weight. People in some countries spell both terms with a “c.”