Hi Guys, thanks for your posts, the stem is definitely Ti, wall thickness is too thin for aluminium (1.5mm) and it's non magnetic. The finish would be from glass bead blasting or similar to give a uniform appearance to the part. CNC machining of titanium is not too difficult with decent cutting tools & slow feeds & speeds.
Weight is 159g and it feels heavier towards the CNC clamp end.
It's been knocking around the cabinet for years. Here's some more pics, I hope someone somewhere recognises it!