Figuring out the aproximate values for colour afinity shouldn't take that many chromatics. Let G be the probability that a pure dex item will roll a green socket and g be the probability that it will not roll green. Your values should be getting good when G*g*N = 5 where N is the amount of tries needed. Just to take a some numbers, if the probability that an evasion piece rolls green is 70%, you would need about 24 tries to start seeing the aproximate values. If the percentage is higher you need more tries ofc
With 4 sockets on a lot of items, if we can make the assumption that each socket is rolled individually, then you'd only need a 4th of those tries in actuall croms