The model for my replica is a UK metal-detector find with no provenance. It is a Deavy Class 6b brooch? , with multiple collets and no bosses. Made of a copper alloy, it is 2.5cm in diameter and 7.5mm tall. It has two tall collets for now-missing stones, and the collets contain white paste. The ring has been decorated with blind drilling and file-work. The pin is missing.
Original Replica
Construction
I decided to cuttle cast my replica, as it is a medieval technique that I have some familiarity with.
Cennino d'Andrea Cennini (c. 1370 – c. 1440) describes "di seppia, di quella che gli orefici adoperano per improntare", "cuttle such as the goldsmiths use for casting (impressing)".
Medieval cuttlebone mould in the Museum of London
I took a pet-store purchased cuttle bone, and sawed the end off, using a hacksaw. I then cut it in half (badly, but that didn't affect the process).
I took the antique brooch and pressed it into one side of the cuttle. Next, I cut pouring gates in both pieces, and air vents in the impressed half. I bound both halves together with masking tape, and pushed it into a sand-filled replica medieval pot. I then melted some bronze (using modern equipment), and poured it into the inlet.
I tossed the cuttle into a bucket of water, and waited a moment for it to cool. Opening it revealed a successful cast.
I cut the sprue off, and finished and polished using modern tools. I drilled out the collets to match the original, as the casting process filled in the holes.
I chose to set green glass cabachons in the brooch. In the regulations of the Goldsmiths of London, it was forbidden to set real gemstones in anything but silver or gold: "'ne dreit piere ne fust assis en latout n'en quivere..."? Most of the surviving glass stones in my annular brooch collection are a particular green, which I was able to match closely. I cemented the cabachons into their collets with a mixture of Plaster of Paris and casein glue, as this seems to produce a good match to the cement often seen in surviving brooches, and is similar to both traditional jewellery practice and medieval glues.
I finished the brooch by fitting a sharpened brass wire pin.
