Cup with Running Ibexes second half 12th century To create "silhouette ware," an object of white clay is covered with a special black slip made with the mineral chromite. The slip is carefully removed or incised to create an image. After an initial firing, the vessel is dipped into a transparent turquoise glaze and fired again. In addition to creating a striking color contrast, this overglaze saturates the chromite slip, transforming it from a matte gray brown into an intense black.. Cup with Running Ibexes. second half 12th century. Stonepaste; incised decoration through black slip ground under turquoise glaze ("silhouette ware"). Attributed to Iran, probably Rayy. Ceramics