Light blue seems to have a problem with light exposure. Harvey's had a light blue Siagon Nugget on the roulette display board from 1967 to 1983. When the chip came off the board one side was still lt.Blue, the exposed side (exposed to fluorescent light for 18 years was a faded light-light white. Hot stamp was not effected. The chip was under plastic protective sheet but still faded. I think some colors bleach easily in sunlight - and fortunately most casinos are not outside.