The dynamic design of this brooch is known as en tremblant (French for "to tremble"). These kinetic jewels feature elements attached to a trembler—a material that acts as a spring—to create lively movement in the jewel as it is worn. This 19th century example features a carved mother of pearl fly resting off of a gold, teardrop shaped base with lovely filigree and detailing. Gilt base metal, 1 1/2" long.