If you fancy something different from the OEM gear knob, I have these nismo gear knobs in stock:
Polished Aluminium
viewtopic.php?f=180&t=59505
Carbon Fiber
viewtopic.php?f=180&t=59504
Black Aluminium
viewtopic.php?f=180&t=62068
It should wash off if it's a masonry paint, but that's not the point........Get on to the company that did the painting, there business insurance/public liability insurance should cover any damage.