I have a sneaking suspicion that we’re going to get a whole arc about the “off colour” Gems this season. I’m not sure why - Steven Universe just seems like the sort of story where a fifth-act viewpoint shift to a completely different planet where we follow a new group of characters we’ve never seen before and have no reason to care about, yet who will inexplicably become more popular with the fandom than the ostensible core cast is the sort of thing that happens.
In “The Test,” Steven realizes that the mission to the Lunar Sea Spire was in fact a test, so he requests a new one. Amethyst creates her own contraption based on Raiders of the Lost Ark, but Garnet and Pearl re-create the obstacles from “Serious Steven,” which was his first serious mission. By letting Steven re-experience the “serious” adventure, Garnet and Pearl wanted Steven to easily defeat the obstacles and still feel that he was overcoming something serious while. As a result the contraptions and Steven’s experiences in the two episodes mirror each other.
I relate to Pearl in a lot of ways but one of the things I probably relate to most is her uncanny ability to stick her foot in her mouth and say the absolutely wrong thing in any situation, especially when actively trying to be helpful
The white pyramid gem in Serious Steven is White Diamond. This explains why White Diamond is still included in the logo, they know she wasn’t shattered, but may be unsure of her whereabouts. They may assume she’s on some cosmic mission, spreading their empire and scouting new planets for resources, who knows. But the diamonds don’t mention that it’s odd that she didn’t show up at the trial. This leads me to believe they may think they know where she is.
In Egyptian culture, a pyramid is a tomb for a pharaoh, who were often seen as God like entities, much the way the diamonds are viewed by their subjects. This pyramid is in the middle a gem battleground.
My theory is that white Diamond was poofed, and the homeworld gems created this pyramid to keep her gem safe, hence the traps, while she healed enough to regenerate. If pearl can take 14 days to regenerate, a diamond of such massive size could easily take much longer. When the corruption song blasted the earth she became stuck in the temple.
Gems can still use some abilities while in gem form. Lapis could manipulate the images in her mirror, and the dessert glass could still build. Lapis was not corrupted but it was confirmed that the desert glass is. It stands to reason that the pyramid gem would still be able to use abilities while in the pyramid, using it as a beacon of sorts.
Many people have speculated that white Diamond has abilities over the mind, the same way blue has abilities over emotions and yellow has abilities over the body. The combination of these three blasts could cause all the symptoms we see of corruption.
I was unsure about this theory when it was originally circulating because of the size of the gem and shape in the pyramid, but as we’ve gotten a better understanding of the diamonds there seems to be more and more evidence to support. Blue and yellow both have different shaped diamonds. Blues is more tear shaped and yellows is longer and thinner, so there’s no reason whites couldn’t be more square. To combat the size issue- we’ve finally gotten an upclose comparison of Steven to blue diamonds gem in the hour wanted special. Both the pyramid gem and blue diamonds gem are roughly the size of stevens head, as pictured in the screen shots above. This assumes steven still isn’t doing much growing, like Greg shows us in stevens birthday photo book.
The shape of WD on homeworld was confirmed not to be a statue. I believe it’s whites ship. It’s entirely possible that her MO is to use a smaller more discreet ship for scouting.
TDLR: Pyramid Gem is WD, she’s was poofed and put in the pyramid as a safe place to regenerate. Gems can still use powers while in objects or corrupted, playing her part in the corruption song. As we’ve seen diamonds are not all the same shape. The pyramid gem is roughly the same size as BDs gem.