People have been going on for ages saying that this is White Diamond due to the diamond-shaped facet of the gem and its size relative to the rest of he gems (the stone being nearly the size of Pearl’s head)

people tend to forget though that both the obelisk and the mural depict this gem with the stone at her sternum

but her mural on the moon base shows her with her gem on her head.

Gemstones don’t change location during shapeshifting, fusion, or regeneration, but different gems of the same kind are mostly identical with the exception of gem location

Do you know what this means? There could be TWO white diamonds!

Oh, and it gets crazier. Notice the position of their hands in every image? It’s the same gesture pearl makes when summoning her weapon.

In the moon base we don’t see a gem, but we see between her hands a circular shape that according to my color-sampling software much brighter than any other part of the mural (no, I don’t mean the part pearl illuminated).

This is open for interpretation, but I think this is a depiction of her summoning a weapon or item from a second gem at her torso. That bright circle is a stylized representation of the glow cast by her gem as she does it.

In other words, that is a fusion of two White Diamonds!

It makes perfect sense if you think about it, it would be weird if there were two identical leaders with the same office and mind. Fusing them together simplifies things considerably