Antique French Guilloche Enamel Locket Ring, circa 1880. The cover of the secret compartment is decorated with a diamond flower (rose-cut diamonds) on a royal blue guilloche enamel ground. This type of rings is also known as poison rings. The shoulders are finely chased with stylized flowers and foliage in Art Nouveau taste. The ring is set with a miniature glazed compartment suitable for a miniature portrait. 18 Karat greenish yellow gold.