To the untrained eye, it can be difficult to tell pure solid gold from fake gold, gold mixed with other metal, or cheaper metal plated with a thin layer of gold. Depending on the quality of the piece, the test can take just a few seconds using common household items, or may require additional materials to get definitive results. Test jewellery you're unsure of before getting costly appraisals, or just to confirm that the gold is pure.
Hold a magnet near the piece to test the attraction. If the object sticks to the magnet, it is not pure gold, but gold plate or another metal mixed with gold. However, if it doesn't stick to the magnet, it doesn't necessarily mean that it's real; more testing is required.
Rub the gold against a piece of glass (use a piece that isn't valuable, such as a glass plate from an unused picture frame). If it scratches the glass, it is not pure gold, since gold is a soft metal. If it doesn't leave a scratch, it still may not be pure gold.
Scrape the gold against a piece of unglazed porcelain tile and look at the mark it makes. If the mark appears grey or black, it is not pure gold. If the mark is yellow, it's gold. Keep in mind that it's still possible that the item is gold plated and may not be solid gold.
File a small section of the gold in an inconspicuous place using a fine metal file. Pure gold, as a soft metal, will file relatively easily. If filing causes the gold to flake off, of if the metal is very hard to file, it is not pure gold.
Conduct an acid test. Put on gloves and safety glasses to begin the acid test, which can be done with a kit or by purchasing hydrochloric acid at a hardware store. Break the tip off a cotton swab and dip it into the acid. Drip a very small amount of acid on the area of the gold that has been filed in an inconspicuous place. If the gold starts to break down, it's not pure gold. Pure gold will not be damaged by the acid.
Be very careful not to get acid on your skin or in your eyes.