Counterfeit gold bullions come out all the time. Caution is therefore called for, especially in the current gold rush, for example when buying on the Internet. There are several ways to detect a gold bar as a counterfeit. Weighing, as I said, doesn't help. Because tungsten has a weight similar to gold. Melting down but is not practicable. With the help of ultrasound or by drilling into a bar, it would be possible to track down the wrong bar.