Collecting 101: Ironstone
From about 1835 to 1860, octagon-shaped dishes were especially popular in table ware and much of the ironstone china was produced in that form by the various Staffordshire potters, including Wedgwood and Spode. The Mason family retired in 1851, selling their pottery to a corporation headed by a member of the Ridgway family. Ironstone china popular with Americans included transfer-decorated dishes in the Willow pattern, some American blue and white historic and scenic designs, usually done in deep blue, and even copperlustre ware patterns. Generally most ironstone bears a marking, a diamond-shape with circle above enclosing a Roman numeral. It is by these numerals and letters with which the date of dish can be told. The potter's mark is impressed in an area below.
Most ironstone china bears the mark of its maker and, from 1842 on, a design registry may be present if the piece is of a special shape or pattern. When unmarked, weight and feel of a piece identify it as the lovely, heirloom it is.