that post on colour i reblogged the other day is good. i started thinking about the color symbolism a lot though and i wanted to add my own thoughts i suppose. these are just loose musings.
black is death; the rings turn black when their wearer dies, the black roses are associated with the hundred dead boys. the black roses are sort of like coal, which is also black, and made of dead prehistoric creatures, as referenced in nemuro's energy speech. those boys are used to fuel a fire also. chigusa wears black, as does movie!touga, who also rides a dark horse in ep. 35. black is also the hidden, like mikage and mamiya, or like the shadow girls. utena also wears black... maybe because of her whole coffin experience? or maybe because black is also, as a secondary meaning, the color that represents the first stage in the alchemical process and thus represents origin and latent forces. (the stages are black-white-red-gold FYI. sometimes green is before black also).
white represents the concept of "the prince"; this is why dios and akio (when he is playing prince) wear white, and why akio rides a white horse. it's also why white is the colour for the student councils' shirts, and especially ruka and touga who wear white pants. shiori plucks a white rose for ruka when they challenge utena, which is the prince's rose, but he has a blue one during the actual duel. utena also uses a white rose because she wants to be a prince. when spinning roses or rose borders come on screen for touga, they are sometimes white, and that's when he is playing prince or when someone is seeing him as a prince. white is both the color of fencing uniforms and of lab coats; i think both of those are sort of prince-aspiring activities. white and paler colors can also be death too though... like the white sheets on movie!touga, or the way that dios/akio has paler hair than anthy. the prince was dead all along, after all.
brown is ordinary. it's wakaba, it's onion boy, it's every background character. it's neutral and means nothing.
red is used in a lot of places but i think one of its clearest meanings is seduction or sex; i think it has that meaning when a red rose spins for akio or touga, and also why the sex car is red. i agree that it is violence also though, since red is the color of blood. it's also power. i mean those concepts are all interlinked in the above cases. as akio's colour, i think it is associated with him as "evil god" - when he talks about how his name means lucifer. when anthy stabs utena her dress spread out looks like blood coming from the wound. anthy's short red dress when she is stabbed with the swords i think is also red for the wound. red is also the prototypical rose color, which is why anthy's rose bride dress is red with green details, it is what the audience expects to see from a rose-themed character. red is the penultimate alchemical stage before gold (akio never reaches it).
i agree with the other post about yellow representing youth since it is nanami's color and that is her main theme. but i also think it is "fool's gold" because it appears gold but isn't. sort of like the fancy sebsastian dior cowbell that nanami wears. because she is a fool. i think there is a great association of innocence with ignorance. when yellow appears elsewhere (like when keiko wears it), it is in association with nanami. but on tsuwabuki it also is youth too. on wakaba's princess dress i think it has the "fool's gold" meaning - that is, being a princess is a false dream to have. kanae's hair is also yellow i think for that reason.
orange represents the juri. she owns that colour. i think it is interesting that given her associations with heraldry, princeliness, and the middle ages, that she is assigned a non-standard heraldry colour, one that is generally absent from the heraldric world altogher. orange was not even recognized as a separate colour with its own word until quite late in both english and japanese. i think the non-standard-ness might mark her difference, as a lesbian, and perhaps exclusion from those traditions. the other character who wears orange is kanae. i think kanae is also a lesbian (awesome). i read in this 18th century alchemical work that orange represents desperation... it sort of fits, to me.
blue and greens were the hardest for me to think about... i think culturally japan has a different blue-green color distinction than in the anglophone world at least traditionally. so i can't help but feel that sometimes perhaps i am not dividing these colors up correctly!!
that teal colour/seafoam green is the ohtori uniform color, and i think that just represents ohtori/the system of family, patriarchy, etc. that one teacher's hair is pretty close to that color. also that stupid ball akio wears in his hair. young touga wears that color. there are also some other scenes where it shows up like when touga is in the shower and nanami is staring at him, and it kind of looks like a cage.... hmm. something there.
green proper, like saionji's hair, i definitely don't see as the same color, i'm sorry </3. they look like different colors to me. he is very invested in the system though so it does make sense for him to be green in that regard. the frog that harasses chuchu is representative of saionji. he might be green because he is jealous of touga. green is also associated with inexperience; and saionji is like that too, and i think inexperience is also why tsuwabuki's dueling outfit is green. but akio and anthy's eyes are also both green. on anthy's dress, as i mentioned above, i think it represents the vegetal as in the rose garden. in western thought green was also associated with death too, because of putrefaction.
i don't think blue is innocence... at least not straightforwardly. yeah, miki is blue, and utena has blue eyes. maybe it is innocence in those cases, or naivety. but kozue is blue, kanae's mother's hair is blue, and also that mf ruka is also blue (with a pale streak because he is close to death). chigusa from the game is blue, but hers is a paler ice-blue because she is a ghost. miki is blue like the day sky and kozue blue like the night sky. i think she is associated with the moon (utena asks about siblings in kozue's episode and akio compares siblings with the moon). she is also associated with water. in real life, blue roses are impossible, so as a symbol they usually represent something equally mystical or impossible (like the holy grail). i think that is why nanami's scenes where she is imagining people finding out about her egg are blue (because they are imagined). there is definitely contrast between juri and some of the blue characters; especially juri and ruka. i think there is a contrast between juri's feelings on miracles with the literal impossible blue rose. blue has also in western tradition been a symbol of devotion. mikage wears a blue jacket, but i think it is just a paler version of utena's black one, the same way his hair is paler than hers, because he's a ghost, though it probably has the impossible blue meaning too.
purple akio and anthy's color. i think it has been historically associated with magic. and it's also power too. when other characters have purple in their design, i think they are in reference to those two. i.e. touga's eyes reference akio, and nanami's reference anthy. i think whenever nanami wears purple that is also a reference to anthy, as her character foil. saionji 's are purple in mimicry of touga's, but also because of his desire to control anthy. when kanae wears purple, like in the movie or in her dueling outfit, i think that's also a reference to one or both of those siblings as well.
there are a number of characters that are not-quite-purple; namely shiori, but also tokiko and mari. that color, which i will call mulberry, is sort of purple-ish. and i think it is like murrey, which is a heraldic stain, which means it's basically a non-standard or not real heraldry color and is fake and lame. okay well not really, but some writers about heraldry write that they represent dishonor on the part of the bearer (which is why they are called stains). even if that was not actually true of the real middle ages, it's still kind of interesting to me. tokiko is sort-of-purple because she is associated with akio. shiori's and fake!mamiya's are because of their associations with anthy. fake mamiya is literally anthy in disguise, so he gets fake purple.
pink is utena's color, and it is also femininity, like when she is in a pink dress, or when a pink spinning rose for her is contrasted with a white spinning rose for touga. that might seem bad, but it's actually the prince role that is bad, and women are awesome. those pinks are usually paler than the pink of utena's hair anyway, which also might symbolize death as discussed above, but in the sort of "princess = living corpse" way that comes up at the end of adolescence. also, i've read that in some schools of gnosticism the colour pink was associated with flesh and hence with resurrection; i think that symbolism holds true in rgu (especially given the other gnostic themes). so leaving the coffin is associated with pink, and anthy wears pink at the end for that reason as well as for utena.