Solid gold is available in different standards of purity. The legal minimum in the U.S. is 10 carats — 10 parts gold per 24 — while the maximum you are likely to encounter is 22 carats. All of these are considered real or genuine. This differs from gold plating or cladding, in which an extremely thin layer of gold is applied to the outside of an otherwise wholly base-metal object. There are some simple steps to help you tell the difference between real gold and cheap imitations.
Check to see if the item has a hallmark that indicates that it has met a legal standard of purity. The mark can be written in carats, in which case the number will be followed by the abbreviation “ct,” “kt” or “K.” It can also be written as a three-digit number which gives the standard of purity, or “caratage,” as parts per thousand (see Resources).
Compare the weight of the item you think might be gold to that of another, similarly sized object which you know for certain is base metal. Use a set of sensitive scales, if possible. Weigh the objects in the palm of your hand. An item made of gold will weigh distinctly more than a comparable base-metal item.
Scratch the item with the point of a pin. If the point sinks smoothly into the metal, the item is made of gold. If the point simply judders along the top without penetrating, then the item is base metal.
Buy a gold-testing kit from an online jewelry-accessories store. This consists of a selection of acid solutions, each of a strength to identify a different caratage. Apply a droplet of the acid to the metal. The item is not gold if a strong, black discoloration results. No reaction at all gives you a positive match for the presence of gold and for the caratage (see Resources).
When performing the scratch test on an item, remember that the softer the metal, the greater the purity.