Known best for his mobiles, Calder also dabbled in the intimate and personal craft of jewelry making. The majority of these works were done in the early 1940s after an exhibition solely devoted to jewelry in December of that year, in the gallery of Marian Willard in New York. His designs started with coiled brass wire and eventually evolved into the flat, hammered look that is present in these pieces. Unlike his contemporary Harry Bertoia, Calder preferred to make his jewelry by hand, often seen carrying around a spool of wire and plies in order to work spur of the moment. Much of his jewelry was made for friends, including the artist Georgia O'Keeffe, and he enjoyed personalizing them, often spelling out the receiver's initials. Calder did not permit duplication or mass production of his jewelry; those in possession of these one-of-a-kind handmade masterpieces either bought them through a gallery or were given them by Calder himself. His trademark spirals and rosettes may hark back to his Scottish origins, but he was also inspired by both ancient and modern cultures from across the world.