Unnatural hair colours did exist in the past!
Yes they did, Older women where often seen with a blue or lavender rinse on their white/gray hair.
My grandmother told me that when she was a young woman in the 30s and early 40s that it was quite popular for a time for 20s and 30s aged women to go with an extreme platinum look like Jean Harlow and wear a bright colored rinse over the top (just like the ones above) for a fashionable change.
Good Housekeeping, 1951
Britling on the Highlands Cafeteria,