Bought this curio more for the clasp on the back rather than the front!. Possibly mother of Pearl? And sadly lost its jewels :-( Can it be dated reasonably accurately by the pin or the Patented Knitless VeilHolda on the back?
Googling "Knotless veilholda" there are a number of matches with the exact writing on the reverse. This would have been a "mourning" pin from the early 20th C. Without the original stones, unless the metal is gold, etc., guessing not much value, almost wonder if there were opals or similar in there that someone removed. You can see a number of sold "knotless veilholda" pins on Worthpoint. Was designed to hold a mourning veil with out having to knot it. I've never seen one before.
The rim is silver although that was a surprise. I bought it (from the bargain tray)because it was interesting and the pin on the back was a little work of art in itself.