Re: Well to be honest, it was dealing with photographs
"Just think about Apple which is a rainbow. (I believe it was in a circle, but I haven't seen it for years)"
The original was an apple with a bite out of it with six color stripes, no gradient. Inspired by Beatles "Apple Corp". They got sued several times by Beatles.
Curiously the order is Green, Amber-Yellow, Orange, Red, Violet, Cyan!
A rainbow would be Red, Orange, Amber-Yellow, Yellow, Green, Cyan, Blue, Violet (with no steps, pure graduation of millions of hues in reality). There is no magenta in a rainbow, as those "colours" are mixes of red and blue parts of spectrum with no green part of spectrum. Because we have three overlapping sensors peaking in Red, Green and Blue, the "magenta" is a sort of optical illusion. With a prism it gives light at both ends of spectrum and gap in the middle.
[Apple also pinched iPhone name from Cisco and iPad name from Fujitsu and their clock's appearance from Swiss Railways. Ives minimalistic white styling is "homage" to the designs Dieter Rams did for Braun, nothing original]