Gold! Well, maybe. Many a gold miner has been fooled into thinking he's found gold when it actually come across precious metals that resemble gold, referred to as "fool's gold." Another unfortunate occurrence is buying gold jewellery that was, in fact, only gold-coloured--but how do you tell?
Test gold by looking at the "gold" in the sun. Gold should retain its colour in the sun as well as the shade. Many metals glitter in the sun, but gold isn't one of them.
Stick a sharp needle or pin in the gold. If it fractures or cracks, it isn't gold. Gold is malleable, meaning it can bend and be dented but it doesn't crack easily.
Gold is heavy. It will sink to the bottom and stay there. If you are gold panning, a great test is to rock the pan back and forth with some water. Gold should stay at the bottom and not move around much.
A sure-fire way to test gold is to wear it on your skin. If your skin turns a greenish colour, that isn't gold you are wearing, but more likely another metal with possibly a bit of gold content. A pure gold piece of jewellery will not react with skin.
Try running a magnet over the "gold." Precious metals like gold and silver are not magnetic, so if your "gold" is attracted by the magnet, that isn't a good sign. Of course, if it isn't, that doesn't guarantee it is gold. Lots of things are nonmagnetic, like wood.
The best way to test gold is to take it into an expert to be tested. Experts have sophisticated acid tests that can determine the exact gold content and tell you the gold price per gram and how much your item is worth.
Do not put bleach on your gold. There is a common myth that gold will not turn colour in bleach while other metals will. This is false. Bleach will tarnish and possibly damage your gold, especially if it is fine jewellery.