Lots of people believe that rose is pink diamond and originally so did I, but after reading forums and watching the show all of evidence points towards rose 'killing' pink diamond. It would explain why pink diamond was taken out of the diamond symbols and why Rose was an outcast. In one of the recent episodes in Season 3 episode 23 "Earthlings"
Jasper, just before she's fully corrupted she yells "becuase of what you did to my diamond" then went on to say " My diamond, your diamond, pink diamond". Obviously rose quarts did something very bad to pink diamond which completely debunks the theory of rose quarts being pink diamond because there is evidence of them being 2 seperate gems.
In the episode "Serious Steven" mural inside depicts Rose Quarts fighting White Diamond using what looks like a pink diamond. It looks like she is using the diamond as a weapon. The show has yet to explain how/if that is possible but having pink diamond in her gem form instead of a body shows that pink diamond's physical form was destroyed.
Now in the recent episode back to the moon its confirmed she shattered Pink Diamond but the new question is why? Did she shatter pink diamond before or after she fought white diamond? Also who/what is lion?
Correct me if I'm wrong/ add anything useful