Marks have been applied to porcelain in the following ways: by incision on soft (unfired) clay, one of the oldest methods of marking; by impressing a stamp in unfired paste, a common practice from the mid-18th century onwards; by painting or transfer-printing under the glaze, which was done exclusively in blue before 1850 in reference to Chinese porcelain, and in various colours after 1850, when chrome-green was used at the...