The smoke is just that, smoke colored (ie greyish). It allows the natural color of the light emitted by the VFD through. This light is white/green - same as is typically seen on consumer video/audio units.

For any other color you need a colored lens - which by definition isn't 'smoke'.
You could of course combine the smoke piece with a inkjet transparency in your wanted color, but the only reason I can see for using the smoke piece instead of the clear in that case would be that you thought the brightness with only inkjet transparency & clear screen was to high...

/Michael