gems, corundum, history.1, methods of fashioning.9

“And take a large clean mussel shell, heat it and put in wine vinegar, afterwards take the shell and make it into a powder and take crystal glass, also powdered”. These instructions on how “to counterfeit pearls” were noted down in a sixteenth-century manuscript now in Museum Plantin Moretus in Antwerp. The neat manuscript lists an array of recipes, including two that describe how to counterfeit pearls, along with a list of alchemical symbols, a drawing of an oven to bake painted glass, and instructions on how to make or improve upon pigments, discern fake from real stones, gild metal, and make ink, mirrors, enamel, and resins. Although the name “P. Koldenbergij” was written on the document at some point, it was previously unidentified. It has been claimed that it must have been in the possession of Pieter Van Coudenberghe (1517–1599), the Antwerp apothecary and botanist with an international reputation who corresponded with savants all over Europe. However, based upon a comparison with a handwritten letter by the apothecary, it can now be attributed to Van Coudenberghe himself.