The pressure/vacuum refrigerant gauge I have mounted to my pressure pot has this handy coloured scale around the outside of the face: green for vacuum, blue from 0 to 55PSI, yellow from 55 to 65PSI and then red to the upper limit. It's a perfect scale for quick glance checks as I just want to make sure that the needle reaches the blue to yellow transition!
It's one of these: , although note that the gauge thread is 1/8" BSP, so a 1/4 to 1/8" bush is required to suit the standard 1/4" fittings
Oh yeah I can make that....