Sterling Brutalist Nailhead Ring Size 6 3/4

Beautiful and unusual vintage Brutalist nail head style ring in sterling silver. Narrow but with a bold look, marked with hallmarks inside the band I cant decipher -- a crown next to a mark in a circle I cant see. Also marked "Ster". Measurements: Approximate size 6 3/4, and measures 1/2" wide on top. Weighs one gram on my scale. Condition is very nice with some moderate to heavy tarnish.