used the golden touch electronic gold tester many times but does not give true reading . gold that are 14-18k gold do not line up with this tester plus some of the gold filled items test as real . i have also test with acid and alot of the times it does not match up with this unit . been all over the web and can not find any users reviews either here on e-bay . i wonder why ? seem to hear of reviews on other testers but this one . in my working with the golden touch electronic gold tester i think it was a waste of my money and all my time trying to make it work the way the instructions tell you to use it . good luck to all who decide to waste their time and money on it too ! if you own one of these tester and are having the same problems then you know what i mean ! junk for the money ! thanks to all who have read what i had to say !!!!!!!!