Dating vintage jewelry safety pin clasp
Many jewelry styles do tend to overlap so always check the entire piece for clues.One of the most obvious date and value tips is antique jewelry marks. Surprisingly enough, a lot of antique jewelry was marked in the most unusual of places so check along the edges, inside of the bale, the pin stem and even on the back of the pin stem!If you see a marking such as "1/20 12K on Sterling" then 1/5 of the piece is 12K gold and is likely to be from 1942 to 1945.
These small differences could answer your questions and drastically influence the value of a piece.
Fine Jewelry containing Diamonds or Precious Stones such as Rubies, Emeralds and Sapphires are either bezel-set, inset or set with prongs and will always have open-backs for maximum brightness.
Air bubbles seen in stones is a clue right off that the piece is glass.
The "C" clasp is another indication that the piece is old.
Remember that there are always exceptions to the rules since the "C" clasp was also used later on in Europe so take every detail into account to come to your full conclusion.