en trem·blant | ˈen träm-blän
A movable, trembling effect, generally achieved through the use of coiled springs of metal, mounted underneath the portion of the brooch that is intended to move
The en tremblant effect refers to a specific type of trembling effect in a piece of jewelry. Most commonly, this was done with brooches, starting in 18th century Paris. To create the en tremblant effect, jewelers would mount parts of a piece of jewelry on a coiled spring which would then allow the piece to move in accordance with the wearer. This would bring the piece to life, giving more volume and brilliance to a piece that would otherwise remain still. The technique was used most often for floral motifs such as flowers, as well as wings such as those on butterflies. The style returned in the 1950s and 1960s when Bulgari produced a series of tremblant brooches.