How to recognize gold?

You’ve just inherited your great-aunt Yvette’s entire jewelry collection. Among the costume jewelry and relics of another era, you’ve spotted a few pieces that make you wonder what they’re worth. Is that chunky gold-colored necklace real gold? And is that cuff made of platinum, palladium or perhaps gray gold? Let’s look at a few simple ways to test the quality of your gold jewelry yourself, at home.

Contents:

• Look for the hallmark
• Testing gold with vinegar
• The magnet test
• Bleach to identify gold
• Ceramic
• The bite test
• The polishing cloth

Look for the hallmark

This should be the first thing you check. Gold jewelry, like silver jewelry and other precious-metal jewelry, is routinely hallmarked. A hallmark is a mark on the metal that verifies its quality and authenticity. So, if you’re wondering, “How can I tell if it’s gold?”, the quickest and simplest answer is: look for the hallmark.

Keep in mind that in France, this mark is only required on jewelry containing more than three grams of gold. Pieces containing less may therefore have no hallmark.

It now gives you two clues:

• the gold content of your jewelry;
• whether your piece is genuine.

This is where “karat” comes in—not “carat,” the unit used to measure diamond weight, but a measure used in jewelry to indicate a metal’s purity. Karat is abbreviated “k.”

Which hallmark goes with which gold karatage?

There are two types of hallmarks used to authenticate gold-alloy jewelry. The first is the maker’s mark (for the manufacturer) or responsibility mark (for the importer). It is generally diamond-shaped.

The other is called a “fineness hallmark” or “guarantee hallmark.” Applied by customs authorities, it varies according to the gold content of your jewelry:

• 24-karat gold: a seahorse. But pure gold is too malleable to be used in jewelry.
• 18-karat gold: an eagle’s head.
• 14-karat gold (about 58.5% gold): a scallop shell.
• 9-karat gold (at least 37.5% gold): a clover.

Testing gold with vinegar

Yet more proof that vinegar really can do just about anything: you can even use it to test your jewelry. Place your gold-colored pieces in a container of vinegar and leave them for at least an hour. Then rinse them with water.

Do you notice a change in color? If so, your jewelry isn’t gold. If the color hasn’t changed, there’s a good chance it’s genuine gold.

The magnet test

Today’s little science lesson: gold isn’t magnetic. So what does it mean if your chunky gold-colored signet ring sticks firmly to a magnet? Yep, brace yourself for disappointment.

If your gold-colored necklaces, pendants or bracelets stick to a magnet, they aren’t gold.

Bleach to identify gold

Here’s a tip you’ll often come across: soak the jewelry in a bleach solution for 24 hours and see whether it oxidizes. We strongly advise against it. Chlorine attacks the metals in gold alloys (copper, silver and others). It can dull and weaken a piece of genuine gold jewelry and damage any gemstones set in it. You could end up damaging the very piece you were trying to assess. Check the hallmark, try the magnet test or ask a jeweler instead.

Ceramic

First, a word of caution. The ceramic test for identifying gold jewelry should be a last resort, as it can damage your precious piece.

To do this test, you’ll need a piece of unglazed ceramic. Rub your jewelry against it and examine the result. If a gold-colored streak appears on the ceramic, your jewelry is gold; if it leaves a black streak, it isn’t.

The bite test

It’s the test you see in movies: bite the jewelry and look for teeth marks. Pure gold is indeed very malleable… but jewelry is almost always made from a much harder alloy (18 karats or less), and some nonprecious metals can show teeth marks too. The result? An unreliable test that’s more likely to damage your jewelry… and your teeth. Best left to the movies!

The polishing cloth test

This test is quick and easy: all you need is a small polishing cloth of the kind typically used to clean jewelry.

Rub your ring, bracelet or long necklace with the cloth and check the result. If the gold-colored layer has dulled or another color shows through, your piece is unfortunately not solid gold. It’s likely gold-plated, meaning it’s covered in a very thin layer of gold that can wear away.

You can also leave this to a professional jeweler or a gold buyer. They’ll test the gold for free, so you won’t pay for the assessment, and you may avoid accidentally damaging your jewelry.

Finally, keep in mind that solid gold and gold-plated jewelry are two different things. Gold-plated jewelry is made from a brass alloy (copper and zinc) coated by electroplating with a thin, 3-micron layer of gold. There are also many varieties of gold used in jewelry: black, yellow, rose, white and even rhodium-plated gold, produced through rhodium plating.

Once you’ve sorted through and authenticated your pieces, don’t let them knock against each other or oxidize in the open air. Store them in a beautiful compartmentalized jewelry box to help your precious pieces keep their shine for years to come.