Just a thought: in my reading about the brain and perception, one of
the things that came up was that people remember colors wrong.
The brain always remembers colors as more saturated than they really
were. So your guy may “remember” olive-oil green, but it may well
not have been that color, really. If that’s the case, you’re never
going to match what he remembers, because he’s wrong.
Get it as green as you can, (w/silver) and then call a line at that