What is 18 kgt jewelry?

WITHOUT ACID,OR OTHER TESTING IT IS HARD TO DETERMINE THE PURITY OF GOLD, IF ANY IN ANY GIVEN ITEM.Many hallmarks,G.F.,18KGT .950 etc,enough to fill a phone book.If you really, really want to know electronic testing of any gemstones is generally an indicator.A reputable pawn shop might be able to help you out.