KTE = Karat Electroplate. This marking appears on "costume" jewelery made of inexpensive base metal (such as nickel alloy) which is then electroplated with gold of a particular karat signified by a number, perhaps 14 or 18. Thus, the marking might read 18KTE to legally divulge that the item is not solid gold, but an extremely thin layer of gold electroplated onto other, less costly metal.

My guess is the mark you are seeing might be KTF which is the earliest mark for Trifari jewelry. The initials stand for Krussman, Trifari and Fishel who were partners in the company.