"Rose gold," which is sometimes referred to as pink or red gold, is one of several popular gold alloys used in making jewelry. In fact, there is no such thing as “pure” rose gold. Even the yellowish gold color most people associate with gold is really a combination of gold and other metals. Pure gold is too soft to use in making jewelry or coins.

When jewelers create rose gold, or gold of other colors, they add alloys that give the metal its distinct color and make it stronger and more durable. The higher the copper content, the redder the color. Substitute aluminum and gold will take on a purple tinge. Mixing gold with other metals produces shades ranging from white to greenish yellow or even black.

A common recipe for rose gold is 75 percent gold and 25 percent copper, and this mix is typically 18 carats. The highest carat version of rose gold, known as crown gold, is 22 karats. A 24-carat gold piece is about 99 percent pure gold.

The simplest way of determining the purity of any piece of gold jewelry or coin is to ask a jeweler or other specialist. Or look for a stamp or laser engraving on a piece of jewelry marking its carats (or “fineness”) stamped on it at the time it was made.

If you want to do your own test, first decide whether you want to keep the piece of jewelry. Many tests of the purity of gold destroy the item tested.

Instruments such as x-ray spectrometers can analyze gold without destroying it. There is also the Archimedes Density method, so called because the ancient Greek scientist is said to have determined the purity of a king’s gold crown by measuring how much water it displaced. Every metal has its own unique density.

Perhaps the simplest and oldest test of the purity of gold is the “touchstone” method. A gold coin rubbed against a dark stone creates streaks on the stone. The amount of copper in the streaks indicates the amount of alloy in the piece.

Today’s high-tech world has led to the development of many kinds of chemical and electronic test kits for evaluating gold. Testing systems vary in price from modest to high, but they will allow you to test the purity of gold you own.

However, if you admire the beauty of your rose gold ring, keep it polished and clean and just admire it.