Board Thread:News and Announcements/@comment-27628871-20151218220901/@comment-26202330-20151227163431

Heinsk wrote: Welp, since you guys still aren't convinced, just keep on mind she didn't know about the Crystal Gems (revealed on Marble Madness) and, also, she wasn't created time after the rebellion (as stated on Catch and Release).

So either way, adding her in that episode would blow the plot (they might add other peridots tho).

I think any Gem who wasn't fighting in the Rebellion (i.e Jasper) know about the Crystal Gem. Homeworld are probably quite embarassed by the whole thing and keep the information stored away in some database or somesuch. It is probably not common knowledge.