Of a Thousand Lands

currently not completely figured out but atm J. A. is queen and it miight just be an alternate Earth.

I'd put it in the multiverse/parallel worlds category, as it's similar to but not our universe.

Sort of explained by Fortune Arabesque Casagan.

From the beginning, it has always been a system of color. No, not a Red Rising sort of system, but a fair, just one. The gods blessed specific colors with their own abilities, their own fortes. Amethyst ruled over all, a color only carried through royal lines (expand here). Fortune explains this as so as not to incur something like, communism, let's say, although it's known differently over there (as Una points out). Magic has never really been a thing - sure, people tried to dabble in dark arts, though they were usually stopped as soon as somebody knew.
Look, it was... peaceful, it worked well, it served the needs of the people.
They went to school, went into their careers, fell in love - all the normal things you'd think of.
But something failed recently, or at least that's the best explanation given, even by Fortune and Cy. Genetics, maybe, some unknown factor. Or maybe it's just been something hidden for all of time, erased from history.

no... hahhaha

It's not really magic, but eye color plays a huge role in this world - for some reason they affect a person's skill. Generally -
Violet ~ Rulers; Wisdom and Judgment, can practically see through lies [ex. Jacquelyne Roman/Hazel Roman]
Gray ~ Commanders; (Military) Strategy [Alex Roman] [And, although his eyes are closer to blue, Andrew Bateman]
Brown ~ Warriors; Darker = Swords [Sarah Victoria Bateman - against her color, black] [Jem Bateman], Lighter = Archers
Blue ~ Sailors or scientific work; Honestly some are born for the sea while others are born for science XD [Una Bateman/Cyrus Casagan]
Green ~ Writers or artists or musicians [Fortune Arabesque Casagan/Abby Rose Bateman]
Black ~ Advisors; of any sort [SV ought to be here]
OFC this is general, like some can be other things [cough SV] cause I didn't cover all the stuff.

And then... there's Bryan... the whole point of the story.