smoothing marble

["justin rego" <justinrego@zzzzzzzzzzz>]

I am working on my first marble sculpture (previously I have only worked
with alabaster) .... it is Portoro marble, a dark grey with gold streaks
.... it is very hard for marble (I think) as it dulls my chisels very
quickly .... i.e. I have to regrind them (I use 3 points) every hour or so
....

anyway, I will soon be finished roughing out the sculpture (it is a
grotesque) and there will be several very hard parts to smooth ..... How do
I smooth marble in general and especially the hard nooks and cranny's? With
alabaster, I used rifflers and a rasp/files .... moving to sand paper .....

however, I test sanded this marble with my rasp and riffler and they do very
minimal grinding, and definitely dull the riffler and files extensively ...
I put in an order for diamond hand pads, a set of 5 I believe for 80$ ....
should I go out and buy more diamond tools, i.e. diamond coated rifflers etc
... ? Are these necessary for working with marble?

P.S. I do not use power tools...looking for a method usable with hand power
only .... Thanks! Justin