<p>The term Off-Coloured in SU doesn't mean "Different coloured", it means "Gems that don't fit Homeworlds ideals". In this case: Yes, Gems <i>can</i> "become" Off-coloured. Rose and the Crystal Gems did so the moment they rebelled.
</p><p>But in your definition: I don't know. It's been theorised that Eyeballs colour looks more faded then the other Rubies because she is older. So it is possible.
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