This distinctive pearl necklace was provided by Joseff of Hollywood, who designed jewelry for many films during Hollywood’s Golden Age. Joseff was not contracted to a studio, and thus rented his jewelry out to various productions.
The above necklace first appeared on Kay Francis as Donna Lucia d’Alvadorez in the 1941 adaptation of Charley’s Aunt. The second time it was used was for the 1952 adaptation of Daphne Du Maurier’s novel My Cousin Rachel. The necklace was worn by Olivia de Havilland as Countess Rachel Sangalletti Ashley, and this time it features somewhat in the plot of the production. Richard Burton’s character gives the necklace to Rachel as a symbolic gesture that he wishes to marry her, which sets the remainder of the story into motion. The passage in the novel describing the necklace says:
There were four strands. They fastened around the neck like a band, with a single diamond clasp.
The description in the novel obviously does not match its representation on screen, but it is a beautiful necklace none the less.
To learn more about Joseff of Hollywood jewelry, you can visit their official website, or read Jewelry of the Stars: Creations from Joseff of Hollywood by Joanne Dubbs Ball.