Another way to arrange them is to take colour out of the equation and sort by "value". Turn your picture black and white and sort that way Like so:

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Now sort from lightest to darkest That's what the "Ruby Beholder" does (there's another tool that I don't remember) and some people swear by that for picking fabric colours. I always just take a black and white picture with my phone and judge that way, no extra tools or gadgets required!