Usually, world-changing moments squeak by with no one paying attention until the instant it's over.
This was not one of those times.
The tone of the discussion between the quartz and Pink Diamond had long passed polite and was currently departing insubordinate. If it wasn't for the fact she lacked an offensive weapon, she'd likely have been removed several exchanges back. As it was, other quartzes were shifting uneasily, getting ready for Pink Diamond's word. And the argument itself was one most of them had been having among themselves, more and more as the centuries wore on, and now at last they were seeing it reach Pink Diamond herself.
So when it happened, a crowd was there watching Pink Diamond and hanging on every one of quartz's increasingly loud words. They could guess the outcome for both the quartz and the planet, but it was still worth seeing play out, and something unexpected could happen - the quartz might realize she'd gone too far in time to stop.
The pearl at her side was a lot less important objectively, but pearls are meant to be noticed. So when this one did a showy, perfect twirl and began to summon some item - it could be anything, really, pearls were just so fascinating like that - from her forehead, the gems watched that too.
And that's how everyone saw the quartz's hand reach for the glowing hilt in the instant between indistinct shimmer and full materialization and then swing, nicking the cheek of the now still pearl and slicing through Pink Diamond's projected body to strike her gem itself.
A lot of them imagined they could hear the soft ting of a crack in that instant.
Everyone heard it when Rose Quartz brought the sword down and sent pink diamond fragments across the platform.
