It is crucial that as a gold buyer you can make the distinction between "counterfeit" and "copy" bullion coins. A "copy" is generally a coin that is using the design of another coin. There are many private legitimate mints that produce "copies". A "counterfeit" is made to intentionally deceive the buyer.
One of the easiest ways to detect a counterfeit bullion is to weight it. When dealing with the exchange of bullion, simply determine the weight. The standard weight for a bullion is 1 troy ounce, which equals 31.1 grams. Don’t confuse the troy ounce with the avoirdupois ounce, which weighs 28.3 grams.
Another obvious counterfeit coin characteristic is incorrect diameter and thickness. Counterfeit coins are often times altered through diameter and thickness in order to add weight. All government coins have standard dimensions that can be found in coin catalogs or online.
Every metal has a distinctive sound and while this is not the best way to test an item, it can be an added measure to ensure what you are getting is real. The best way to hear legitimate silver or gold is to flip it. Both pure gold and silver will ring in the air. Counterfeits will not make a sound.
A common practice in geology is the scratch test for identification. Gold will leave a yellow streak when scratched against a surface. This is not a recommended practice since scratching can devalue your item. Not only that, plated counterfeits will most likely pass this test.
Buying and selling precious metals is a technical process, but common sense can be a highly valuable asset to the buyer and seller. Using trusted sources, researching your item, and following best practices can save everyone time, money, and embarrassment.