Look at it very closely under a magnefying glass. look for tell tale marks left by the maker. Is it very very smooth? are the angles very accurate? any solder or welds? LOL does it have a 14k stamped in it LOL? all marks of a manufactured piece, not that it's not valuable but indicates that may not have been hand made like INca or Indian artefacts.
Hand made stuff will have little imperfections like small dents in the gold from the hammering, or the stone won't be a mirror finish, only polished because they didn't have cerium oxide, tin oxide, or cromium oxide and a lapidary wheel to polish it.
Some people can even tell if the maker was left or right handed by the marks he left behind...