Board Thread:General Discussion/@comment-5492692-20150406053754/@comment-26037921-20150410214625

Lapis has been trapped in the mirror for possibly thousands of years, as some other Crystal Gem had imprisoned her in there, not the modern ones, so it must've been around the Great War that Lapis was trapped. Since Peridot didn't know anything about them before Marble Madness, I strongly believe they don't know each other.