Hall-marks, or PLATE-MARKS, are authorised legal impressions made on articles of gold and silver at the various assay offices in the United Kingdom for the purpose of indicating to the public the true value and fineness of the metal of which they are composed. The marks are a series of symbols, which are stamped in an embossed style extending in a line of about one-half to three-quarters of an inch in length, the size of the marks varying with that of the articles on which they are impressed. They are usually stamped on every separate piece that is used to compose or make up an article. These symbols have the following representation: (1) The maker's mark, which is the initials of his Christian and surname, used since 1739. (2) The standard or Her Majesty's mark—viz. for gold of 22 carats, a crown and 22; for gold of 18 carats, a crown and 18; for gold of 15 carats, 15 and 625; for gold of 12 carats, 12 and 5; and for gold of 9 carats, 9 and 375. These standard marks represent England; they are different for Scotland and Ireland. In the Edinburgh assay office the marks are: for gold of 22 carats, a thistle and 22; for gold of 18 carats, a thistle and 18; for gold of 15 carats, 15; for gold of 12 carats, 12; and for gold of 9 carats, 9. For Glasgow they are: for gold of 22 carats, a lion rampant and 22; for gold of 18 carats, a lion rampant and 18; for gold of 15 carats, a lion rampant and 15; for gold of 12 carats, a lion rampant and 12; and for gold of 9 carats, a lion rampant and 9. For Ireland the standard marks are: for gold of 22 carats, a harp crowned and 22; for gold of 20 carats—extra standard for Ireland only—a plume of feathers and 20; for gold of 18 carats, a unicorn's head and 18; for gold of 15 carats, 15 and 625; for gold of 12 carats, 12 and 5; and for gold of 9 carats, 9 and 375. For England the silver standard marks are a lion passant for metal composed of 11 oz. 2 dwt. of fine silver to 18 dwt. of alloy, and Britannia for 11 oz. 10 dwt. fine silver to 10 dwt. alloy. For Scotland, a thistle for 11 oz. 2 dwt., and a thistle and Britannia for 11 oz. 10 dwt. at the Edinburgh assay office; and a lion rampant for 11 oz. 2 dwt., and a lion rampant and Britannia for 11 oz. 10 dwt. at the Glasgow assay office. For Ireland, a crowned harp for 11 oz. 2 dwt. No new standard of 11 oz. 10 dwt. is assayed and marked in Ireland. The figures in the gold standards denote the number of carats fine there are in any article bearing them, pure gold being reckoned at 24 carats; so that if a piece of gold-plate or jewelry is marked with a crown and 18 it indicates that it consists of 18 parts of pure gold and 6 parts of some other and inferior metal. This alloy would consist of three-fourths gold and one-fourth alloy. Gold as low in fineness as 9 carats is now legal, and as it is marked by the assay authorities there can be no deception if the public rightly understand the hall-marks introduced for their benefit. If they do not, then they are likely to be deceived. Nine-carat gold is a little over one-third pure gold. (3) The hall-mark of the assay towns: London, a leopard's head; Birmingham, an anchor; Chester, a dagger and three wheat sheaves; Sheffield, a crown; Newcastle, three castles; Exeter, a castle with three towers; Edinburgh, a castle; Glasgow, a tree, fish, and bell; Dublin, Hibernia. (4) The duty mark: the Queen's head, or head of the reigning sovereign, introduced in the year 1784. (5) The date mark: each assay office has now its letter or date mark, changed every year; 20 to 26 letters of the alphabet being used in rotation, and repeated in different styles of letter. In London the assay year commences on the 30th May, and is indicated by one of twenty letters of the alphabet, A to U, omitting the letter J. The question has been raised whether the hall-marking system ought not to be discontinued.
The following table (made up from Cripps) shows specimens of the different alphabets used by the Goldsmiths' Company of London as date-letters from 1478; variety in the shape of the shields being also used as a further distinction:
| D 1478 to 1498—Lombardic, caps., double cusps. | A 1696 to 1716—Court hand. |
| B 1498 to 1518—Black letter, small. | E 1716 to 1736—Roman, capitals. |
| A 1518 to 1538—Lombardic, capitals. | e 1736 to 1756—Roman, small. |
| F 1538 to 1558—Roman and other caps. | g 1756 to 1776—Black letter, capitals. |
| a 1558 to 1578—Black letter, small. | a 1776 to 1796—Roman, small. |
| H 1578 to 1598—Roman, capitals. | A 1796 to 1816—Roman, capitals. |
| D 1598 to 1618—Lombardic, capitals, external cusps. | M 1816 to 1836—Roman, small. |
| C 1618 to 1638—Italian, small. | A 1836 to 1856—Black letter, capitals. |
| a 1638 to 1658—Court hand. | b 1856 to 1876—Black letter, small. |
| Q 1658 to 1678—Black letter, capitals. | M 1876 to 1896—Roman, capitals. |
| q 1678 to 1696—Black letter, small. | a 1896 to 1916—Roman, small. |
The accompanying figure shows a Birmingham silver plate-mark. 1, the maker's initials; 2, the standard mark; 3, the hall-mark of Birmingham; 4, the duty-mark; 5, the date-letter for the year 1889.
See Cripps, Old English Plate, its Makers and Marks (1878; new ed. 1889); and Gee, The Hall-marking of Jewellery practically considered (1889).