Base diameter is 4cm/40mm. This is an unusual fragment of a fluted vessel: a small part of a concave circular base extends out into at least three more like four vertical flutes. The vessel's exterior appears to be imitating metal with a dark burnish/polish. Looks to be a kind of chisel/pointed tool to create the furrows between ridges. Elizabeth Carter has dated a similar fluted vessel from Susa to the Achaemenid period. This sherd will go for INAA analysis.
From Interior to Exterior