Rubens has been recognised as an artist of extraordinary erudition as well as a collector, diplomat and linguist. Unsurprisingly the main focus of Rubens scholarship has been iconographical. By focusing on material I address an aspect of Rubens’s life and work that has by comparison been largely ignored. Antwerp, the artist’s home city, was a major centre for global trade in precious stones. There is evidence that the artist not only owned raw stones but dealt in diamonds. During the first two decades of the seventeenth century at which time Rubens was a visitor, Rome was a centre for the development of mineralogical science and collecting, not least through the Accademia dei Lincei with whose members Rubens was associated. By focusing on Rubens’s interest in traditional lapidary matters as well as in nascent scientific enquiry, and by attending to pictorial detail, I aim to shed light on how the artist not only acquired and valued minerals but how precious stones were thematised in portraits and subjects from mythology and the Bible.