Gold fingerprinting is a method for identifying a particular item made of gold based on the impurities or trace elements it contains.
Method
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is used to characterize a gold-containing item by its trace elements, a.k.a. fingerprinting the sample by mineralizing event and to the particular mine or bullion source.
This technique has been used to lay claim to stolen or relocated gold. Even gold that has undergone salting can be identified as to its multiple sources.
References
Gold fingerprinting Wikipedia(Text) CC BY-SA