Antique 9k yellow gold onyx signet ring with an "M" monogram from the United Kingdom c 1920s.
Great antique condition
Size: 10.25 resizable*
Weight: 4.9 grams
Band: 18.2 mm (front), 4.5 mm (back)
Onyx: 17.1 mm x 10.8 mm x rectangle cut
Hallmarks: 9ct