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How to Tell if Gold Is Real

originated by:TheGirlThatShines, Maluniu, Anonymous, KP (see all)

A 2004 investigation revealed that more than half of 22 jewelry stores around the US were selling "fool's gold" and passing it off as real.^[1] By American standards, fake gold is anything less than 10 karats. If you're wondering whether your gold is real, the most reliable way to find out is to take it to a jeweler and have it tested, but they will charge a fee for this service.

edit Steps

1
Inspect high-friction areas for discoloration. If the item is plated, that's where the plating will begin to rub off. Discoloration proves that the gold is fake, but the absence of discoloration doesn't prove that the gold is real.
2
Hold a magnet up to the item. Gold is not magnetic, so if it sticks to or pulls toward the magnet, it's fake. If it doesn't react to the magnet, however, it could still be fake--just made from a non-magnetic material.
3
Test the density.
- The density of gold is about 19.3 grams/mL, which is much higher than most other metals. Take the gold piece and weigh it. Then submerge it in a graduated vial of water and note the variation in volume. Divide your weight per volume variation (water level after gold submerged minus the water level before, in mL). Anything close to 19.3 grams/mL normally shows correct density, needless to say that you need a precise scale and vial for this method. Alternatively if you are measuring a solid for which the formula is known, you could use a caliper to determine its volume. Find the mass of the gold in grams, and then put some water in the graduated cylinder. It doesn't matter how much, but note of the amount in milliliters. Then put the gold inside the water (this won't damage it) and note the new water level. Get the difference between the two numbers in mL. Based on these two measurements (mass and volume), calculate using the formula: Density = mass/volume. If the answer is close to 19 grams/mL, then it is probably real gold, or a material close to the density of real gold, of which you can search for on the periodic table and use alternate tests to see if it is these metals instead. Remember your measurements will not be exact.
- While it may be hard to measure the volume of a liquid displaced by a small piece of gold, here is an example calculation: Say a solid gold piece weighs in at 38 grams and then displaces 2ml of a liquid in a graduated cylinder of liquid. If you do the math, Density = Mass / Displacement - then 38g/2ml=19g/ml which is close to the density of gold.
4
Use the classic "plate." Use a piece of unglazed ceramic material. Rub the gold against it. Fool's gold will leave a black streak, and real gold will leave a golden streak.
5
Use Nitric Acid. You can also apply nitric acid to the item to see if it's real gold but nitric acid is hard to come by, and it's easier (and safer) to just have a jeweler do it. Gold is insoluble in nitric acid, which dissolves silver and base metals. This property is exploited in the gold refining technique known as "inquartation and parting". Nitric acid has long been used to confirm the presence of gold in items, and this is the origin of the colloquial term "acid test", referring to a gold standard test for genuine value.
6
A very rough way to check the density is to compare the item to one that's similar in size and that you know is real gold. They should feel equally heavy. If the item in question is noticeably lighter, it may very well be fake.

edit Tips

The presence or absence of a hallmark indicating the number of karats is meaningless. A fake gold piece can have a fake hallmark, and a real gold piece can have no hallmark.
You can also apply nitric acid to the item to see if it's real gold^[2] but nitric acid is hard to come by, and it's easier (and safer) to just have a jeweler do it.
When shopping for jewelry, reputation can be key. Most of the larger "chain" stores (for example, Jared's) have nothing to gain by selling fake gold jewelry. They depend on their reputation to attract more customers.
Avoid the jewelry kiosks in markets and malls as the likelihood of low quality or fake jewelry can be higher.
Karat: When we say 24kt or 24k Gold jewelry, we mean that all the 24 parts in the gold are just pure gold without traces of any other metal(s) or 99.9 percent pure. When we say 22kt or 22k Gold Jewelry we mean that 22 parts of the jewelry, is gold and the balance 2 parts are some other metal(s) or equal to 91.3 percent gold plus 8.6 percent of some other metal alloy When we say 18Kt or 18k Gold Jewelry, we mean that 18 parts of the jewelry is gold and the balance 6 parts is some other metal or equal to about 75 percent gold plus 25 percent of some other metal alloy We can roughly state that each Karat is equal to approximately 4.1625 percent. The difference of the other metal or alloys of the metal, gives the jewelry its hardness and color. We can state that 24 Karat is the softest and 10 karat the hardest, because 10kt would have 41.6 percent gold and the balance would be other metals which are mostly harder than gold.. The color from the other metals enhances the beauty of the jewelry as the case may be, white gold, yellow gold, red gold etc.
24k is pure gold but too soft for use in jewelry or coinage. Because of this other metals are added to add consistency and thus making for different densities. This fact makes the dispersion test work but makes it not as as precise as suggested. This is a very good way of testing newly mined gold in the field as this is 24k pure gold. Regardless of this, there are very little metals denser than gold and so as a rule of the thumb the higher the density, the purer the gold.
guide for precision:
With regards to the gold jewelry in Europe, they placed markings so as to indicate the golds purity. This marking is in the form of a three-digit number. The markings are as follows:
10 karat 417 marking; gold purity is only 41.7 percent
14 karat 585 marking; gold purity is only 58.5 percent
18 karat 750 marking; gold purity is only 75 percent
22 karat 917 marking; gold purity is only 91.7 percent
24 karat 999 marking; gold purity is only 99.9 percent
In Portugal gold is mostly 80% pure or 19,2 k and comes typically in three colours:
Yellow - Composed of 80% pure gold, 13% silver and 7% copper.
Red - Composed of 80% pure gold, 3% silver and 17% copper.
Grey or white - Composed of 80% pure gold alloyed with palladium and other metals, mostly nickel.

edit Warnings

The density test will be very imprecise if the gold has gems or other materials as their density may be different from golds. The density test will also wield different values according to pureness.
Many chunky looking pieces of jewelry are in fact hollow, to save weight and therefore cost. If air is entrained in the piece, this WILL invalidate the test, as the air will add buoyancy and increase the volume when the item is immersed in water. The density test is only valid for solid items, or for items from which all the air can be expelled by allowing water to fill the entire internal cavity. A small bubble of air left inside will result in an inaccurate result.
Nitric acid is highly corrosive. Precautions should be taken if it will be used for testing. The gold itself is safe as it is insoluble in nitric acid.
These tests may not be able to differentiate solid gold from a tungsten plug covered by real gold.
If there is a cavity, this will result in lower density than solid gold while still being almost pure gold by mass.

edit Things You'll Need

Magnifying glass
A magnet
Precise gram scale
mL graduated vial or Caliper
An unglazed ceramic material.
Nitric acid

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