Okay, first off...
Excellent pics of his underside! Most definitely male!
Truth of the matter is that color changes can happen a lot in crays for varying reasons; many of which are environment-related. Either way, it is not a sound method for identification purposes. Sure, familiarities with various colors along with patterning can often provide one with a fairly decent narrowing down of things based on a quick glance at the specimen in question. But for an accurate I.D., we will need close, clear pics of form I gonopods (which you would need to raise using a toothpick or similar instrument).
Looks good!
BV