I dont buy pearl being a diamonds pearl for a few reasons

Diamonds seemingly have one pearl, at least as far as we know, and i feel it holds true for pink and white, those pearls are probably well known amongst gems and i think holly agate would have recognised her if so

Secondly, i doubt a diamonds pearl has had much interaction with a random rose quartz, so i cant see how pearl would have met and been around rose if she was a diamonds personal pearl

Lastly, something i noticed about pearl is that she looks different to other pearls, the other pearls seem to look about peridots size where as pearl seems really tall when comparing how they are drawn

I think this might mean pearl could be an off colour, this would maybe explain why she met rose and grew affection for her as rose would most likely treat off colours kindly, i also get the feeling pearls never actually served a diamond, she has good buolding knowledge but seemingly no idea of gem tech actually works, this is noticable when she is baffled at controlling the hand ship and working the door pads in the zoo

Im sure theres probs a few things wrong with what im saying but this is just thr feeling i get from pearl