What is a Diamond Mark?

During the period 1842-1883 the British Patent Office issued a diamond mark along with the registration number when a design was registered.
As well as showing that the design had been registered, diamond mark offered the buyer the reassurance of knowing an item was of British design. It also 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. 
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.
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.

 

 

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How to understand the mark?

1) What 'class' is the material?

 

2) What year range is the mark from?

There are two ranges of year codes; 1842-1867 & 1868-1883. At first glance they look the same but if you look closely you can see that some have a number at the right hand corner and some have a letter.

If there is a number at the right hand corner of the diamond then it is in the 1842-1867 range

If there is a letter at the right hand corner of the diamond then it is in the 1868-1883 range  

 

number at the right hand corner of the diamond 1842-1867 range letter at the right hand corner of the diamond 1868-1883 range

 

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3) Understanding marks 1842-1867

First of all make sure there is a number in the right hand corner as shown below:-
If there is a letter then the mark is 1868-1883

You can ignore the number at the bottom of the diamond - this tells us how many items were included in the registration, (sometimes known as bundles or packages).
From the other numbers and letters we can work out the date of the registration.

Day - Right hand corner -  this is self explanatory

Month - Left hand corner -  this is worked out from the code below:-

Month letter	Month		Month letter	Month
A	December		H	April
B	October		I	July
C	January		K	November
D	September		M	June
E	May		R	August
G	February		W	March

 

 Year - Top of the diamond -  this is worked out from the code below (they are listed in alphabetical order):-

Year codes for 1842 - 1867 Year codes   Year codes   Year codes A 1845   J 1854   S 1849 B 1858   K 1857   T 1867 C 1844   L 1856   U 1848 D 1852   M 1859   V 1850 E 1855   N 1864   W 1865 F 1847   O 1862   X 1842 G 1863   P 1851   Y 1853 H 1843   Q 1866   Z 1860 I 1846   R 1861

Exception Notes:
In 1857 the letter R was used during 1-19 September, and during 1860 the letter K was used for December.

registration date for this mark:
27th April (H)  1847 (F)

just to prove it works.....!
Jones & Walley put both the date and
the registration diamond to give the following:-
13th May (E)  1843 (H)

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4) Understanding marks 1868-1883

First of all make sure there is a letter in the right hand corner as shown below:-
If there is a number then the mark is 1842-1867

 

You can ignore the number at the left hand corner of the diamond - this tells us how many items were included in the registration, (sometimes known as bundles or packages).
From the other numbers and letters we can work out the date of the registration.

Day - Top of the diamond -  this is self explanatory

Month - Bottom of the diamond  -  this is worked out from the code below:-

Month letter	Month		Month letter	Month
A	December		H	April
B	October		I	July
C	January		K	November
D	September		M	June
E	May		R	August
G	February		W	March

 

Year - Right hand corner of the diamond -  this is worked out from the code below (they are listed in alphabetical order):-

Year codes for 1868 - 1883 Year codes   Year codes A 1871   L 1882 C 1870   P 1877 D 1878   S 1875 E 1881   U 1874 F 1873   V 1876 H 1869   X 1868 I 1872   Y 1879 J 1880       K 1883

Exception notes:
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.

 

registration date for this mark:
29th September (D)  1879 (Y)

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5) This year table is in chronological order -to help in identifying possible exceptions as shown below:

1842 - 1867 and 1868 - 1883 Year codes   Year codes   Year codes   Year codes 1842 X   1855 E   1868 X   1881 E 1843 H   1856 L   1869 H   1882 L 1844 C   1857 K   1870 C   1883 K 1845 A   1858 B   1871 A     1846 I   1859 M   1872 I     1847 F   1860 Z   1873 F     1848 U   1861 R   1874 U     1849 S   1862 O   1875 S     1850 V   1863 G   1876 V     1851 P   1864 N   1877 P     1852 D   1865 W   1878 D     1853 Y   1866 Q   1879 Y     1854 J   1867 T   1880 J

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.

REGISTERED NUMBERS - from 1884 

Registered numbers are a consecutive numbering system which started in 1884 of designs which were registered by companies. The Registered Number, usually written as Rd on the piece of pottery, gives the date when that design was registered to prevent copying, but it could have been made at any time later than that date.

The table below gives the year and the registration numbers issued during that year
- for example any Rd number from 19756 to 40479 was issued in 1885

1884     1
1885     19756
1886      40480
1887     64520
1888     90483
1889     116648

 
1890     141273
1891     163767
1892     185713
1893     205240
1894     224720
1895     246975
1896     268392
1897     291241
1898     311658
1899     331707

 
1900     351202
1901     368154
1902     385180
1903     403200
1904     424400
1905     447800
1906     471860
1907     493900
1908     518640
1909     535170

 
1910     552000
1911     574817
1912     594195
1913     612431
1914     630190
1915     644935
1916     653521
1917     658988
1918     662872
1919     666128

 
1920     673750
1921     680147
1922     687144
1923     694999
1924     702671
1925     710165
1926     718057
1927     726330
1928     734370
1929     742725

 
1930     751160
1931     760583
1932     769670
1933     779292
1934     789019
1935     799097
1936     808794
1937     817293
1938     825231
1939     832610

 
1940     837520
1941     838590
1942     839230
1943     839980
1944     841040
1945     842670
1946     845550
1947     849730
1948     853260
1949     856999

 
1950     860854
1951     863970
1952     866280
1953     869300
1954     872531
1955     876067
1956     879282
1957     882949
1958     887079
1959     891665

 
1960     895000
1961     899914
1962     904638
1963     909364
1964     914536
1965     919607

 

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Details of the registrations are held at: -  The National Archives, Kew, Richmond, Surrey, TW9 4DU. Tel: +44 (0) 20 8876 3444.

 

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