certainly a member of the Rosewood family easily distinguished while turning by the oiliness of the timber and the smells are distinctive as well. Kingwood or Cocobolo, really a neat pen anyway a rose by any other name.
another vote for cocobolo, but not easy to tell the color from
photos with incandescent lighting. (it adds yellow) but looking
at the hardware (I assume it is gold?) I'd say cocobolo. But if
that hardware is chrome or silver, then you'd have to mentally
subtract yellow from the wood, in which case kingwood is
certainly a possibility. They're in the same general family, right?