Gold is the quintessential symbol of status, power, immortality and wealth, often restricted to royalty.

Accounts differ on when the first gold mines were dug and operated. Some say it all began in 3,100 BCE with the ancient Egyptians. Archaeological sites like the over-6,000-year-old mines of the Asosa region of Ethiopia and the 5,500-year-old Sakdrisi mine of Georgia put the systematic practice of gold mining back several thousands of years earlier. Some say that in South Africa there are mines that are even older.

The ancient Egyptians believed gold was the flesh of the sun god Ra. Gold is considered luxurious and precious because it is beautiful and easy to work. It does not tarnish, rust or dissolve (except by aqua regia, the name for nitrohydrochloric acid, which is used in one of the tests mentioned below). Gold is hard to extract: Barely 50 grams come out of a ton of ore. It is also one of the best electrical conductors, which is why it is used so heavily inside computers and other technological equipment.

WAYS TO TEST GOLD AUTHENTICITY

This article discusses several tests you can easily do at home to help you when you need to know how to tell if gold is real.

The Stamp Test: Look for Hallmarks

A piece of gold jewelry is often engraved with a hallmark, which is a stamp that identifies its content and/or manufacturer. Hallmarks usually appear in an inconspicuous place like the inside of a ring.

The standard purity scales are based upon karats and millesimal fineness. The hallmark test, also known as the magnifying glass test, is a good place to start when checking if your gold is real.

Hallmarks include:

• Valid purity numbers under the Karat system (like 8k, 9k, 10k, 14k, 15k, 18k, 20k, 21k, 22k, 23k, and 24k)
• Valid purity numbers under the Millesimal Fineness system (333, 375, 417, 583 or 585, 625, 750, 833, 875, 916, 958 and 999)
• False purity numbers (anything other than the above)
• Manufacturer (like ESPO for Esposito, etc.)

Hallmarks show the gold’s level of purity and manufacturer to lend greater credibility to a piece’s authenticity and to make it easier to identify and verify. Since anybody can engrave any hallmark they choose, this level of testing is not 100% foolproof

If the numbers say anything other than the ones mentioned above, then you have fake gold. For example, 800, 925, and 950 do not refer to gold, but to silver. Why would they be put 925 on gold? Because this often means the jewelry is gold plated with a sterling silver base.

Another thing to look for is whether or not the marks indicate that the value has either been measured in karats or in millesimal fineness. Any other numbers than those above would indicate that the gold is fake.

Not all real gold jewelry has hallmarks—for example, older pieces may have had original markings that have been worn off.

Look for Letter Markings

Any gold that is marked less than 10k (41.7% purity) is considered fake.

Anyone who is familiar with the different levels of quality will quickly recognize the following markings:

• GP
• GF
• GE
• GEP
• HGP 
• HEG

You will want to avoid the above designations if you’re looking for real gold. They all indicate gold plating. In the same order, they mean:

• Gold Plated
• Gold Filled
• Gold Electroplated
• Gold Electro Plated
• Heavy Gold Plated
• Heavy Gold Electroplated

These markings indicate that only a small percentage of gold was used to cover a piece that was made out of some other kind of metal in order to give it the appearance of gold.

To give you an idea of how the upper levels of purity stack up next to one another: 24k gold is 99.9% pure, while 18k gold is 75% pure. Absolutely 100% pure gold is unheard of, mainly because pure gold is very soft and wouldn’t make for a durable piece of jewelry. 

The Skin Test

Look for Bluish or Greenish Tint on Your Skin

This test is simple: It involves holding a piece of gold jewelry between your hands for a couple of minutes. The perspiration from your hands will either react with the metal and change the color of your skin or leave it unaffected. When real gold is in direct contact with your skin there is no discoloration. If the gold is fake it will cause your skin to turn black, blue, or green at the contact points.

One exception to this procedure occurs if you test gold on your skin while wearing a liquid foundation. When gold touches the makeup it will turn your skin black at the points of contact. Removing all makeup before testing makes this test more reliable.

Alternatively, makeup can also be used to test for gold authenticity. Put on a liquid foundation and add powder over it. Once the makeup has dried, press the piece of jewelry against your skin and then run it lightly over your skin where you have the makeup. If the jewelry leaves a black track on the makeup, you probably have real gold.

Gold is extremely nonreactive, so real gold jewelry will never discolor your skin. But using the makeup test is a unique way to also check if it’s real. 

If there are discolorations in gold jewelry it means you have an alloy where there are other metals mixed in.

The Size and Weight Test

This test works well on coins and bars. You can

• Compare a piece of gold you want to test with one that is already known to be real
• Use a set of calipers and a jeweler’s scale or use a Fisch Tester

Gold is denser than most other metals. If you have a piece that looks too large for its weight or feels too light for its size, then you probably have fake gold.

Bullion coins are actual coins made from precious metals, including gold, silver, palladium, or platinum. They serve as collectibles, investments, or as a hedge against inflation.

The Magnet Test

Hold a strong magnet next to a piece of gold and watch for a reaction. Gold is not magnetic, so there should not be any attraction to magnets. If there is, you most likely don’t have real gold.

However, some of the base metals that can be mixed with gold are also non-magnetic so you can get a false read. The test isn’t foolproof so it’s a good idea to do this in conjunction with another more accurate testing method. 

The Float Test

Just drop the piece into a container of water. Gold is dense. If it doesn’t float at all or hover over the bottom of the container, you could possibly have real gold.

The Ceramic Scratch Test

Take an unglazed ceramic plate or piece of tile and scrape a piece of gold across its surface. Real gold will leave a gold mark or trail. Other metals will leave a black trail.

The Water Test (a.k.a. The Density Test)

This is done by calculation. You need

• A scale (to weigh the jewelry)
• A container of water and
• A way to measure the level in millimeters (to measure the water levels before and after the jewelry goes into the water)

Now do the calculation: subtract the “before” measurement from the “after” measurement. Then divide the weight of the jewelry by the difference in the water levels.

This gives you the density.

The standard density of real gold is 19.3 grams per milliliter (also written 19.3g/mL). Not a lot of other metals come very close to it. If your calculation gives this figure or something very close to it, you probably have real gold.

When you use density to distinguish gold's authenticity, you also need to keep in mind that there can be differences in density between different types of gold.

For example, the purer the gold, the heavier it will be--and white gold is heavier than yellow. Therefore, the density of gold between 14k and 22k will be anywhere between around 12.9 and 17.7 for yellow gold and anywhere between around 14 and 17.8g/mL for white gold.

The Acid Tests

Vinegar Test

This test simply requires that a few drops of vinegar be applied to the metal, hopefully in an inconspicuous place.

If the metal is real gold there will be no change. If the metal is fake gold it will change color.

The Nitric Acid Test

Gold is a noble metal which means its resistant to corrosion, oxidation and acid. To perform this test, rub your gold on a black stone to leave a visible mark. Then apply nitric acid to the mark.

The acid will dissolve any base metals that aren't real gold.

If the mark remains, apply nitrohydrochloric acid, also called aqua regia (75% nitric acid and 25% hydrochloric acid) to the mark. This mixture dissolves gold so, if the mark disappears, the gold is real. 

The Machine Tests

Electronic Tester (i.e Sigma Metalytics Machine)

The Sigma Metalytics Precious Metal Verifier is calibrated for accuracy on a minute scale, enabling it to distinguish between metals in less than one second. While this equipment is good for measuring bullion and coins, Sigma Metalytics recommends the Kee Gold Tester for testing jewelry.

This machine sends electromagnetic waves into the item, passing through surface materials like wrapping or plating to read the resistance of the underlying metal. Its meter display is set to show a specific range of resistance that is or is not consistent with the resistance of each metal the machine has been calibrated to detect.

XRF Spectrometer

This machine works by sending X-rays through the gold and exciting its atoms into a higher energy state.

When the excited atoms return to normal they give off radiation. The machine monitors and analyzes this, using the radiation reading to identify the material. This method is fast and accurate. It is precise and far outperforms other methods while doing no damage to the items being tested.

In fact, none of these methods causes chemical or mechanical damage, so they will not jeopardize the value or integrity of your piece.

The Fail-Safe Test

If you really want to know for sure how much gold is really in your gold, the most tried-and-true method of finding out is to take it to a reputable jeweler and have it tested there.

Jewelers have a wide array of methods available to the public for authentication of gold content. Of course, nothing beats experience. But those who are trying to pass lesser metals off as real gold having become increasingly sophisticated in their “craft,” so even the jeweler will probably resort to machine verification to make sure.

Most home tests can give you an idea of whether or not your gold is real. While they are all good at showing probability, none are 100% conclusive.

The best way to know for sure if your gold is real is to have an experienced and reputable jeweler evaluate it for you.

Please feel free to share this article with anyone you know who could benefit from the information and caveats it contains.