Sapphires were taught from formation to always follow exactly the path of the future which they foresaw. That even slight deviance could cause gross inaccuracies in their predictions, and if a sapphire couldn’t predict the twistings of fate, what good were they? It was why their class of gem had been raised to aristocracy in the first place, after all. A rare but powerful gift.
Sapphire, like all sapphires, took these teachings to heart, and never considered any other way but to accept what fate had in store for her. If she was to go to Earth and be discorporated, well, that was how it must be. How confusing it must be to not have the inevitability of the future there before your eye!
So when the Ruby -- who had been so flustered earlier, and had so valiantly tried to protect her despite the inescapable designs of fate -- lay defeated, Sapphire could not help but to give her some small comfort.
For what could a few words of kindness in her last moments on this world possibly change?