a feature or quality that is typical of somebody/something 特征；特点 - (in the UK)
a mark put on gold, silver and platinum objects that shows the quality of the metal and gives information about when and where the object was made 金银纯度印记（打在金、银、铂制品上，表示纯度、生产日期及产地） Culture hallmarkshallmarksHallmarks are official marks that are stamped into articles made of gold, silver and platinum to prove their quality. Under British law all items made of these metals must be hallmarked before they are put on sale. The marks are very small and are usually placed where they will not affect the appearance of an article.Hallmarks were introduced in Britain in 1300. They are controlled in Britain by the Assay Office. Most modern hallmarks include four symbols: the sponsor's mark identifies the company which made the article; the standard mark describes the quality of the metal; the Assay Office mark indicates the city where the article was tested and marked. A date letter which indicates the year in which the article was stamped, may also be added.The sponsor's mark used to be an emblem such as a bird, but now consists of the initials of the maker. The standard marks consist of a number which indicates the quality of the metal. The number 916, for example, indicates 22 carat (NAmE karat) gold. In the past gold items were marked with a crown. Any silver items are marked with a lion, as well as the number 925, to indicate sterling silver, which is 92.5% pure. Platinum items may be marked with an orb (= a decorated ball with a cross on top). The Assay Office mark was first added in 1478, when all items had to be tested for quality at Goldsmiths' Hall in London (which is why they are called hallmarks). Britain currently has Assay Offices in four cities: the symbol for London is a leopard, for Birmingham an anchor, for Sheffield a rose and for Edinburgh a castle. Date letters are in different styles of type and set inside a shield. Additional symbols may show that the article was made to celebrate a particular occasion such as a coronation or the millennium.In the late 18th and early 19th centuries a system of hallmarks similar to that used in Britain was introduced in the US. Items were stamped with a date letter, duty mark, which indicated that tax had been paid, and a lion. The practice did not last long, and instead goldsmiths and silversmiths stamped their work with their initials or full name. Some added a date, but many items have no date, so their age can only be estimated by the style. In 1868 Baltimore silversmiths were the first to add below their names the sterling standard of 925/1000 (= 92.5%). Silversmiths in Boston and New York had guilds (= workers' organizations) which decided their own standards, and items were often marked with the name of the city in which they were made.Items made in the US now must have on them the mark of the person or company that made them and a standard mark. Gold items are marked in karats, usually shown as 'K‘. Most gold jewellery in the US is 18 karat and marked '18K‘. Silver items of sterling standard may be stamped 'silver‘, 'solid silver‘, 'sterling silver‘, 'sterling‘ or 'ster‘.The idea of a hallmark as a means of identifying the origin and quality of an item has a wider use in English. If something is the hallmark of or has/bears all the hallmarks of something, it has all the essential features associated with that thing. If somebody leaves/stamps their hallmark on something, they have a unique and lasting effect on it.
Word Originearly 18th cent. (as a noun): from Goldsmiths' Hall in London, where articles were tested and stamped with such a mark.