Registered design diamond mark

How to read it

Diamond marks came in with the Ornamental Designs Act of 1842 and ended when the 1883 Act replaced it, The National Archives explains in its guide to the design registers, which it holds. A maker or retailer registered a design with the Designs Registry, part of the Board of Trade, to protect its decoration from being copied; the diamond was printed, engraved or otherwise marked on the object, for example on the underside of china, and showed the design was registered and designed in Britain. The Roman numeral at the top gives the class of material: I metal, II wood, III glass, IV ceramic, V wallpaper, VI carpets, and VII to XIII textiles. The other points give the day, the month, the year and a parcel number, which the State Library Victoria's guide says records how many items were included. By the end of 1867 the year letters had used the whole alphabet, the library explains, so the positions changed for 1868 to 1883. The mark dates the registration of the design, not the making of the piece: Steve Birks's Potteries site notes that a pattern or shape could stay in production for many years after.

Also searched as: british registration mark, british registry mark, diamond mark on pottery, rd diamond, rd no, rd number, registered design mark.

Telling the two series apart

The National Archives gives the difference in one line: from 1842 to 1867 letters were marked on the left point of the diamond and numbers on the right, and from 1868 to 1883 letters on the right point and numbers on the left. Steve Birks's Potteries site gives the same test from the right-hand corner alone: a number there means the earlier series, a letter the later. Apart from the class numeral at the top and the parcel number, the numbers give the day of registration and the letters give the month and the year.

The year letters

The National Archives' table of year letters, by letter:

From 1 to 6 March 1878, W was used for the year in place of D.

The month letters

The month letters are the same in both series: C January, G February, W March, H April, E May, M June, I July, R August, D September, B October, K November, A December. The National Archives notes three exceptions: R was used for 1 to 19 September 1857, K for December 1860, and G for the month in place of W from 1 to 6 March 1878.

Rd numbers from 1884

After 1883 the diamond was replaced by the initials Rd or Rd No. with a number (Steve Birks's Potteries site). The numbers ran in one sequence for everything except textiles: the State Library Victoria's guide dates its start to 1 August 1884, while The National Archives' tables begin it on 1 January 1884. The National Archives' ranges for designs other than textiles are:

The same number can turn up on different designs, The National Archives warns, because numbering restarted under different Design Acts. Later registrations are kept by the UK Intellectual Property Office, the State Library Victoria notes.