No wait, my theory doesn't make sense, the war was already going on when Pink Diamond was killed.

Hm. Bismuth still could've done it though.

....was Rose the ONLY Rose Quartz that rebelled? could a different Rose Quartz Gem have shattered Pink Diamond? I mean, given that most gems are interchangeable and supposed to look the same....its not outside imagination to think that the one who killed Pink Diamond is one of those Roses bubbled up at that station.