First off I’d like to give a shout out to gemsaplenty for giving a shout out to me. This’ll contradict her theory at slight points (this post was percolating in my head before she made hers) but only slightly.

Now if you remember before here’s the serious steven mural:

Three figures with triangles: A white one on the left, a blue one in the center, and a yellow one on the right.

Now one thing of note is that one the floor in the center room of the serious steven temple had a three triangle triforce-esque image:

While a similar triforce thing appears in jail break, but this time in amazing techni color:

And you know what those three triangles are colored? White, blue, and yellow!

Now let’s return to that mural:

This first white gem can be seen in a inverted triangle, kinda like the inverted pyramid that the episode took place in. And you know what was IN that pyramid?

Looks like a white diamond to me.

Fighting Rose Quartz was this figure:

Looks blue. And you know who was wearing what resembled a blue diamond?

And finally on the right we have this:

A YELLOW Diamond. Aka THE Yellow Diamond mentioned by jasper. and both Peridot and Jasper wear a yellow diamond on their essentially matching uniforms.

Speaking of colored diamonds, Let’s look at pearl’s space outfit again:

That diamond is pink, like Rose Quartz.