The record series descriptions in the catalogue give useful administrative histories that will help you to understand how the records were created.
Diamond marks were issued by the Patent Office between 18.
They were issued with the registration number when a design was registered.
Use this guide to find original representations (drawings, paintings, photographs) of trade marks.
The National Archives collection is far from complete, but this guide will suggest supplementary sources for researching trade marks.
*From 1-6 March 1878, W was used for the year in place of D.