Merriam-Webster Collegiate Dictionary - hallmark

 I. noun  Etymology: Goldsmiths' Hall, London, England, where gold and silver articles were assayed and stamped  Date: 1721  1.  a. an official mark stamped on gold and silver articles in England to attest their purity  b. a mark or device placed or stamped on an article of trade to indicate origin, purity, or genuineness  2. a distinguishing characteristic, trait, or feature the dramatic flourishes which are the ~ of the trial lawyer — Marion K. Sanders  II. transitive verb  Date: 1773 to stamp with a ~