1934F103.5 Signet Matrix - Seal Matrix, 1750-1800 Possibly made in Birmingham 1 Presented by Francis Buckley, 1934. A 'signet' or 'seal matrix' is a small stamp used for impressing the mark of its owner in wax onto documents.This is one of a collection of twenty-seven acquired by the museum in 1934. The majority of examples are finely made of moulded translucent glass, in this case translucent blue. Several bear engraved inscriptions in reverse, as in the case of this example. The word 'PRODIGIOUS' and design of a male figure with raised arms may have had some specific significance at the time.