What brand of bike was it?
On Triumphs, it is a pain - at least on my Tiger. It depends on how the dials are lit. On my bike a standard incandescent bulb lights the back of the dial face. The numbers and marks are translucent green - thus the green colour. You can get Narva brand arctic blue bulbs that give a whiter and brighter light and you can also get Narva brand silicon bulb covers that are like little coloured bulb condoms. They convert the bulb to blue, but this just makes the green dials a little bluish green.
I think you need to replace the dial face plate to get a true colour change - but I could be wrong.
The people to ask would be a car cosmetics shop that do the lowered Japanese hot hatches (like in the Fast and Furious movie). These guys seem to know no bounds in vehicle modifications.
Here is a website that has funky gauge faces for bikes
Gauge face replacements. Click on the "Motorcycle gauges" link. They have stuff for the usual sports bikes, but they do make custom gauge faces. Check the custom link. You could have Tiger stripes on your instruments!!Anything is possible - how bad do you want it?