Do you remember in the old cowboy movies when the cowboy would “bite” a gold coin to see if it was real or fake? It seems that even back then clever counterfeiters were plying their trade. Nothing has changed since those times and if fact counterfeiters have become better at their craft if nothing else.
The truth of the matter, is that a fake gold coin could easily pass the “bite” test if it was made out of lead, plated with copper, so it could be then plated in nickel, so it could be then plated in 24K gold. Fake jewelry is nothing new but if you buy plated jewelry you want to do it willingly not by being sold something that is being passed off as being 14K or 18K.
Rule number one, is that if you aren't buying a piece of solid gold jewelry from a legitimate source, assume it is fake until you have had a jeweler look at it. Just because it has a 14K or 18K stamp on it means nothing any more, because there is so much fake gold jewelry floating around now.
The same rule applies for any type of designer jewelry, because virtually any type of designer jewelry is now being counterfeited overseas. If you are approached on city street by someone that has an 18K gold chain that is still in the original jewelry box, virtually100% of the time it will be fake.
In the typical con it will even still have a price tag on it and they will say that a friend of theirs recently stole it. Another common item that is sold as the genuine article is fake Rolex watches. It too may come in a counterfeit box but these are easy to spot. This is because, the second hand on a real Rolex “sweeps" while the second hand on a fake will move with a “tick”.