Dating jewellery rings
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.
Some other date and value tips that I've learned over the years are that often Genuine Gold and Silver, even if it has wear, will not show a base metal underneath since it continues all the way through.
Many costume pieces from the nineteenth century and into the Art Deco period were made of gold and/or silver over base metals such as gold over brass, silver over brass, silver over copper, gold over copper, etc.
Attend Antique & Collectable Shows, browse Antique Shops and read jewelry books to familiarize yourself with period styles and their findings.
Since Bakelite is either cast or molded it would not have a seam line anywhere and the workmanship should look hand carved and not be crudely executed as if a stamp was used.
On Vintage Bakelite brooches, the clasp would be embedded into the piece.
The tube hinge was generally used until the 1890s where the safety catch clasp became popular in the Art Deco 1920s period.
Over the years the appearance of the safety catch clasp has changed so it's good to recognize the old from the new.