Simple tests that can be performed at home to identify real gold include checking for markings and magnetic attraction, testing for heaviness and observing nitric acid reactions. Additionally, scratching gold against pottery and examining for signs of gold plating is another method to identify gold.
When attempting to identify genuine gold, first check it for markings. Most gold jewelry possesses some type of inscription denoting the karatage of the gold. Another way to test gold is to hold it next to a magnet. Real gold has no magnetic attraction, so if the "gold" sticks to the magnet, it is not genuine. However, some gold jewelry may have a steel clasp, so do not assume that jewelry is not real based on this test alone.
Next, test jewelry for weight by placing it in a jug of water. Real gold should sink, as gold is a very dense metal. Nitric acid test kits may also be used to determine whether or not gold is genuine. Real gold should have no reaction to the nitric acid.
For another test, scratch the item against a ceramic object, such as pottery, plates or tile. Real gold leaves a gold streak, whereas false gold leaves a dark, or black streak. Examine the item for signs of discoloration in areas of wear, as this is a sign that jewelry is gold-plated. The most certain way to know if gold is genuine is to take it to a jewelry store for a professional appraisal.