Understanding fancy colors

[echelon6]

So there's a fancy scale, I'm trying to understand it both from a pricing and beauty perspectives.

there's light, fancy, intense, vivid, dark, deep - but from photos on various websites I can see the Deep and Dark ones are just darkened of the same hue. If I want only max hue without any brightening or darkening, which grade do I go for? and separately, which grade commands the highest prices, all else equal?

tia