Random idea: volts as Hours amps as Minutes Resulting wattage drives an iridescent bulb
Iridescence essentially would mean it has a groovy, far-out metallic layer making rainbows on the surface. Not bad, but irrelevant.
PS: Neither of those would really communicate the needed information, except as an extreme (11:59 pm would look just like 10:27 pm, but very different from 12:01 am).