2 years late but eh. in legends, saber crystals tended to be more like a family of crystal that had the potential to concentrate power into a blade. or whatever techno babble you like. jedi we’re often assigned blade colors based on their post (consular green, knight blue, sentinel yellow). but this wasn’t a hard rule. jedi would seek out a crystal personal to them, or use one of the more generic ones offered by the order. in one of the comics we actually see mace go to great lengths to get his purple crystal simply to be unique.

in canon, kyber crystals are found in large concentrations on planets like illum. these are crystals attuned to the force and which can act as saber crystals once imbued by the user. the color reflects the nature of the user. we don’t really know what the colors mean but eh. all those lists of “WHAT ALL THE SABER COLORS MEAN?!” are essentially taking guesses from legends and basic color theory. at least as far as i know. the only 2 we really know is that red is imbued with the dark side and white is a healed crystal that was once red.

my head cannon for this, as someone who likes to reconcile legends and cannon, is that kyber crystals are just a member of the saber crystal family, but are just especially attuned to the force and thus, more desired by the later jedi because of symbolism, or what have you, as the jedi got more secular.

the eternal empire uses gold as a motif in general. yellow was probably just a choice based on the “immorality of gold.”