An Art Deco onyx and seed pearl dress set, first half 20th century, comprising: a pair of cufflinks,

An Art Deco onyx and seed pearl dress set, first half 20th century, comprising: a pair of cufflinks, four buttons, two collar studs, each of cut-cornered square outline, centring on a seed pearl on a square section of polished onyx, bordered in engraved white gold, largest 1.1 x 1.1cm, each stamped 18CT PLAT; together with an additional collar stud of similar design, centring on a single-cut diamond, partial British hallmarks for 9ct gold, fitted case