Sherman periscope color

Google image for "M6 periscope"  Many examples.  Heads usually black.  Occasionally OD.  Body OD, knobs dull aluminum.

Thanks HeavyArty, but I meant the body (that's my fault) 

Thanks stikpusher, I also saw them with a OD body and black tips, think I'll go that route

Doing some image searching shows both. Some are all OD. Some have an OD body with both ends in black, and some have one black and one OD end.But it's hard to say when any colors were added or changed. When all else fails, a fallback of solid OD for US Army equipment in WWII is a very safe bet.

and HA's advice of how to do the lens parts is right in target.

The glass was very thick and had a greenish tint.  To represent it, I first paint them black, then a couple coats of clear geen, and finally a couple coats of clear gloss.  It gives a dark geen color like an old coke bottle.  I think it looks convincing.