The set of synthetic dyes we have does a pretty fantastic job at covering all the colors seen in the natural world, plus a whole lot more. We go way beyond the natural world, in fact, when you look at the bright/fluorescent colors you see in an athletic clothing store, as I mentioned in another comment.

What makes that 'new blue' you refer to special has nothing to do with how we perceive it directly -- it's trivial to recreate that hue. It's useful for the very specific use case of mixing colors while oil painting. It's for artists trying to blend colors.