What grits are you sand through? And are you sanding the length of the pen blank after you go round-n-round? I'm seeing a ton of scratches around the blank.
Typically on a dark colored blank I'd skew, sand through MM12(being sure to sand 'against the grain' and wiping the 'grit' off before moving on to the next step) and finally hit it with some MacGuires PlastixPolish(yup, from the automotive store)....
Hope to see more advancements your making soon....your definitely around the top of the bell curve for most learning!
Scott (hope it didn't come out like bashing....wasn't meant that way) B