So I was rewatching Steven Universe and something kind of stuck out.

We have Lapis who explicitly knew who the Crystal Gems were (and how they only cared about Earth and not other gems), Peridot who didn’t and Jasper just referred to them as “Rose’s army”. So its safe to say that Peridot had nothing to do with the war (or came after it idk), Jasper just fought in it, but I feel like Lapis was the most involved since she knew the specific name of their group. Considering her distain for them and Earth I feel like its a safe bet that she wasn’t on Rose’s side so she was probably with Blue Diamond (also considering she’s blue).

When she’s released in Ocean Gem she goes “Do you even now who I used to be?”. So I don’t think that she was just a supporter or follower of blue diamond but she was much more important.

And then in Serious Steven we see this which could be Rose fighting Blue Diamond:

But look under Blue Diamond

She’s drawing up something from the ground that kind of looks like water doesn’t it?

Lapis is a Gem comprised of multiple minerals and associated with royalty and power

What if Lapis is Blue Diamond’s daughter?

Also when she’s being released from the mirror water forms a pattern around Steven 

And it kind of looks like a cut diamond pattern

Just thoughts I had