Gorgeous 10k Yellow Gold & Synthetic Pearl Brooch/Pin, with a very intricate design.
Much research was done to try to identify the Maker, but no luck…it is marked as follows:
T (in a circle), which is unidentified.
k10, which indicates it could be from Japan, early 1900s.
It has a Trombone Clasp/Catch, which is was used primarily from about 1850 to the latter half of the 19th Century, but could be as late as the 1930s, depending on the the Country of manufacture.
And the hinge looks handtooled, rather than machine mass-produced.