Registered Designs: Diamond Marks

Domestic Records Information 101

1. Diamond marks

During the period 1842-1883 the Patent Office issued a diamond mark along with the registration number when a design was registered. See the Research Guide Registered Designs and Trade Marks for details of registration.

Besides indicating that the design had been registered, diamond mark offered the buyer the reassurance of knowing an item was of British design.. It assured the person registering the design a degree of protection from copying. The protection was dependent on the type of material and the class in which the product was placed. See the introductory notes to the record class lists and the entry in section 602/1/1 of the Public Record Office's Guide, Part 1. The mark was created to identify the type of material used (known as the class), how many items were included, (sometimes known as bundles or packages), and the date of registration. Below is a description of the marks and the means to decode them. Note that the registration number does not form part of the mark. The centre is occupied by the abbreviation Rd signifying that this is a Patent Office mark standing for Registered Design.

2. Dating a Diamond Mark

On the Diamond Mark you will see that the year of registration is shown along with the month code. The correct year can be found from the year codes tables on the next page, and the month from its table below. However, you will also see that there are two ranges of year codes; 1842-1867 & 1868-1883. By dint of detective work you should be able to determine the correct year from the design of the Diamond Mark and the placing of the day number. See the diagrams below.

3. Month Codes

4. Year codes

Two sets of year codes are shown. The first, in alphabetical order within the two time bands, is to assist the enquirer when deciphering Diamond Marks.

1842 - 1867

1868 - 1883

The second, in chronological order, is to help in identifying possible exceptions as shown below:

1842 - 1867 and 1868 - 1883

Exception Notes:
In 1857 the letter R was used during 1-19 September, and during 1860 the letter K was used for December. From 1-6 March 1878, W was used for the year in place of D; and G was used for the month in place of W.

(ri2208) Last updated: 10 January 2006 | © Crown Copyright 2002