I may have missed this in an earlier post but…
you said that romelles marks display a her hormones (kinda) and shift to more pink-lavender colors once on estrogen— that all being said; do the alternative marks help identify an alteans sex? Is there a specific color range to determine which “box” someone fits into?
I NEED to make my infographic I'm chomping at the bit, but yes! Altean marks specifically mark the levels of the three sets of Altean sex hormones, showing through in their coloration.
Gender for Alteans is a very fluid thing in general, so the boxed in gender roles that we humans have aren't quite a thing.
That said! I know exactly how the wheel of mark colors works (because I'm me.).
Pure blue marks indicate the Altean masculine gender
Purple are quite literally defined as a "mix" of masculine and feminine (a gender in it's own right, but generally referred to by both masculine and feminine pronouns)
Pink marks are indicative of the Altean feminine gender
Red marks are defined as a "mix" of feminine and third (a gender in it's own right, but generally referred to by both feminine and "neutral" pronouns)
Yellow marks are indicative of the Altean third gender, the humans refer to this as "neutral" or "androgenous" but that doesn't quite encapsulate it.
Green marks are defined as a "mix" of masculine and third (a gender in it's own right, but generally referred to by both feminine and "neutral" pronouns)
There's no strict cut off point for any of these, but adult Alteans have very keen eyes for what shade indicates what. Non-Alteans and children have a very difficult time discerning the differences and usually just trust whatever they're told.
It's a very fun bit of worldbuilding I (Sol) like to toy with!
If you're curious, Allura classes as pink markings and Coran classes as green, Lance gets blue when [spoiler but not how it happens in canon]