This 18k yellow gold ring is set with an oval onyx plaque, which is decorated with a tiny bird inlaid with precious stones, a technique known as Pietra dura. This is an ancient technique in which a hard stone mineral - often onyx - is inlaid with other coloured minerals. Size: US 7, UK N 1/2, circumference 54.5 mm. The setting measures 12 x 10 mm. Weight: 4.30 grams. Age: The pietra dura plaque was made 19th Century, also known as the Victorian era, circa 1860s. It is set in a later ring shank, circa 1960s. Material: Acid tested as being 18k gold. Condition: In good antique condition with minor wear, consistent with its age. Please note that the antique box is for display purposes only.