The valid purity number for an 18K gold is 18K in the karat system and 750 in the Millesimal Fineness system. Anything other than the numbers above are false purity numbers. With hallmarks, it is easier to identify and verify the authenticity of your gold piece, as it shows its level of purity.
If the piece is real gold, the stamp should bear a manufacturer's mark and a karat marking, such as 14K or 24K. Fake gold may bear a karat mark, but will not have a manufacturer's mark.
Look for Stamps or Hallmarks in Your Gold Jewelry
Most real gold is stamped with a hallmark that indicates its purity, aka its karat. The karat is the unit used to measure the purity of gold. The higher the karat, the purer the gold. The most common karats you'll see are 10k, 14k, 18k, 22K, and 24k.
Fake plated gold jewelry that is stamped 14K or 18K is nothing new any more, so you have to be aware of it. That also goes for anything that has a stamp of legitimacy on it. It doesn't take a rocket scientist to manufacture a fake stamp, so they are out there.
Look for a Letter Mark
If the item of jewelry has the letters GP, GF, or GEP stamped on it, these indicate that it is not made of real gold. GP means it is gold plated, GF means it is gold filled, and GEP means it is gold electroplate. That is, the jewelry is made of some other metal with a thin layer of gold on top.
You might not leave a mark on fake jewelry. However, gold-plated lead is even softer than gold, so an extremely deep mark may also indicate a fake. Rather than damage the jewelry yourself, you may want to simply look for marks made previously.
Jewelers often use nitric acid to test their gold. Basically, gold won't react to nitric acid, but all other metals will turn greenish.
Place your jewelry on a table or hold it in your hand, pour some white vinegar on the metal directly (a dropper can also be used) if the metal of the jewelry changes its color, it is not pure gold and if it keeps shining then you have real gold in your hand.
Acid test.
An acid test can reveal the karat of solid gold jewelry, but it can also show whether jewelry is solid gold or gold-plated. With an acid test, a small sample of the jewelry is removed and exposed to acid to induce a color change. The resulting colors indicate which type of metal the jewelry is made of.
18K gold plated Jewelry is not made of gold but base metal or silver applied with a layer of 18K gold by chemical or electrochemical plating.
Hallmarks are imprinted numbers on most authentic jewelry items to showcase their karat percentage. You can expect to see a marking of 24K-10K written somewhere inside of a ring or on the side of a bracelet. These markings may also be written as “750” for 18K gold.
If it's real gold it will not stick to the magnet. (Fun fact: Real gold is not magnetic.) Fake gold, on the other hand, will stick to the magnet. If that necklace leaps to the magnet, your significant other has some explaining to do.
Yes, it can. Even while 18k gold is of greater quality than 14k or 10k gold, it can oxidize and become discolored with time. Take precautions to shield your gold jewelry from the elements and clean your pieces frequently to keep them looking their best for as long as possible.
Heat your gold jewelry with the lighter.
Apply the flame to the jewelry for about a minute or 60 seconds. Watch it closely for any changes in color. Fake gold will get darker, while pure gold will do the opposite: it will get brighter the hotter it gets.
The answer is yes; you can absolutely pawn gold plated jewellery, but it depends on the base metal. Pawning gold plated jewellery is really only ever worthwhile if the base metal of your item is made of a precious base metal like silver.
18k gold is the best when it comes to maintaining the awesome sparkle of pure gold while being durable.
Since this kind of jewelry is made of alloy materials, it is much more affordable than solid gold jewelry. In fact, it tends to cost less than all other gold alternatives like brass, silver, etc.
Because pure gold is denser than other metals, a gold item will sink quickly and directly to the bottom of a tub or bottle of water. Fake gold can float or fall more slowly. Real gold also won't rust or tarnish when exposed to water, while gold plated items can show discoloration.
Nearly all real gold is stamped with a hallmark that notes the karat weight of the jewelry, like 10K or 14K. This stamp is usually found on the clasp of a necklace or bracelet, or on the inner band of a ring.
Fool's Gold can be one of three minerals. The most common mineral mistaken for gold is pyrite. Chalcopyrite may also appear gold-like, and weathered mica can mimic gold as well.