Things You'll Need
Instructions
Senses
Use your senses for preliminary testing on scrap gold. Feel it. Gold feels very smooth, and it flows when heated, so it does not have sharp edges.
Look at it. Check the color. The color is not a gaudy yellow like some imitation jewelry. Look for gold marks. Although this is not foolproof, items incised with a gold content mark are more likely gold.
Check the scrap gold with a loupe or magnifying glass on the edges where wear is most likely. If the edge shows wear, your piece is probably plated gold or costume jewelry.
Acid Test
Purchase an acid test kit. This kit for testing scrap gold comes with a stone and various bottles of acid that test for different karats of gold.
Find a spot that is least visible for scraping. This test is invasive and does some damage to your jewelry or scrap gold. Rake the scrap gold across the stone to make a visible line.
Drop a tiny amount of one of the acids on the line on the stone and watch for the result.
Check to see if the acid dissolved the line, or if the line held without dissolution. If the acid dissolves the line, use the 10-karat acid to test again. If the 10-karat acid solution dissolves the metal line, the scrap is not gold or is less than 10-karat gold. Some old gold is 9 karat, but American standards no longer consider less than 10 karat as gold.
Electronic Test
Purchase an electronic gold tester. This tool operates on batteries and uses a gel to make a seal for testing. If you intend to buy and sell much gold, it is faster and more accurate than the acid test kit, and worth the purchase.
Connect the testing pen and clipboard to the electronic tester.
Turn the pen top counterclockwise to place a small amount of the gel on the end of the pen.
Place the edge of the scrap gold under the clip, and turn the tester on. Touch the pen to the gold and push the "test" button.
Wait for the result. A number will show on the screen. The number translates to a karat amount as shown on the front of the gold tester, so you can determine if your item is 10-karat, 14-karat or 18-karat gold---or somewhere in between those fractional amounts.