Other forms: hallmarks
A hallmark is the tiny official stamp punched into gold and silver to say what the metal is, how pure it is and where it was tested. Turn a ring over, or look inside the back of a spoon, and you find a row of marks the size of a pinhead.
From that came the everyday sense: a hallmark is the feature that tells you what something is, the sign of the maker's hand. Long sentences and a rainy town are the hallmarks of his novels; secrecy was the hallmark of the whole operation. It takes OF, the hallmark of something, and it works in the plural as easily as the singular. There is a verb too, since silver is hallmarked before it is sold. The word carries approval when you use it for craft and stays neutral when you use it for a habit: a hallmark of quality, a hallmark of panic.
1nounstampAn official mark stamped on gold, silver or platinum to certify its purity and where it was assayed.
“The hallmark on the teapot dated it to 1843.”
2nounhallmarkA feature so characteristic that it identifies the thing or person it belongs to.
“Careful lighting is the hallmark of her photographs.”
synonyms: trademark, signature, characteristic
3verbpreciousTo stamp precious metal with an official mark of purity.
“Every piece is hallmarked before it leaves the workshop.”
Goldsmiths' Hall in London housed the assay office, where gold and silver were tested and stamped. A mark from the Hall was proof of purity, and by 1721 the two words had fused into hallmark. The verb followed in 1773, and only in 1864 did English start calling any telling feature a hallmark.
1721. From hall + mark, from Goldsmiths' Hall in London, the site of the assay office, official stamp of purity in gold and silver articles. The general sense of “mark of quality” first recorded 1864. Use as a verb from 1773.
Etymology from Wiktionary, CC BY-SA
Practised in Jewellery & Watches