+1 for the Diamond tool holder from Eccentric Engineering. (See the advert to the right of this page.)
I bought one over 10 years ago when I started out and it is still my go-to turning tool for most materials. They are not cheap but you get the holder, a HSS bit, a grinding jig and an Allen key. All you need is a grinding wheel, which you will need anyway, and off you go.
I now also have some indexable carbide tools for cast iron and a carbide parting off cutter from Arc Euro which I use on most materials.
Hope this helps
Jim