as someone who used to make jewelry i suggest adding something to make it more 'shiny' as a properly done stone would be shiner. Something wore often might become dull like the end result would be considered, however something well kept by someone who uses a polishing cloth after cleaning it daily(im talking like wash it off if you got something on it) or someone who is or would be royal... they would be sure things shone brightly. In full lightings however this would be nearly completely how it would be however, or in a stone the river polished naturally though in water it looks even brighter. It really depends on the intention of the artist. I would just overlay a little of whatever color light your doing over the white which will make that look brighter but will also leave the impression of the color of light which is how that would be. Honestly, i think this is pretty good.