In stormhorns there are cloaks that go by Prismatic Cloak, <color>. Their descriptions seem like they are all part of a poem. Has anyone bothered to put it together? I attempted to search and didn't find much except for people looking for trades. My guess is that they are in the order of the rainbow, I could be wrong though.
 Red: How did the rainbow meet its end
Will the spectrum ever mend?
Green: The rainbow fought;
But the curse was wrought.
Blue: Loyalty betrayed
Lured by the shade.
 Violet: Caught in a prism;
The colors suffered a schism
Grey: Hue lost, the world stand stark;
Trapped forever in the dark.
Green I would think is talking about the Shadow curse on the Shadar-Kai, the Shadar-Kai being the rainbow in this case.
I have no idea where the betrayal of a shade comes about as spoken by the blue cloak, perhaps that's lore I could've caught if I paid attention to the wheloon chain. As for violet, I have no idea how to interpret yet as it's still early for me.
The grey cloak seems to be speaking of Shadar-Kai and how they became bound to the plane of shadow.
While grey isn't part of the rainbow, it does more closely relate to sonic color scheme wise and is almost a symbol itself on the Shadar-kai becoming bound to the shadow plane and afflicted with the shadow curse.
Just my bit on it.