A late George III turquoise and diamond set cluster ring

A late George III turquoise and diamond set cluster ring, centred with a later pear-shaped turquoise cabochon within a surround of cushion-shaped diamonds and further border of smaller turquoise cabochons. Set in a silver and gold closed back mount surmounted with a stylised coronet set with five graduated cushion-shaped diamonds. The pierced foliate shoulders with shamrocks and scroll shank. Size R.