Stamped with an official mark proving quality or authenticity; bearing the characteristics that identify or distinguish something.
From hallmark (a mark stamped on precious metals at Goldsmiths' Hall in London to certify quality) plus past participle -ed; originally a literal quality mark, now used metaphorically.
London's Goldsmiths' Hall gave us the term 'hallmark'—it was literally the place where precious metals got their official stamp, and now 'hallmark' means any sign of authenticity!
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