Me and @jynxcomplex were hypothesizing after today’s episode and so I’m going to put it here– feel free to add on your own thoughts!

So, the diamonds are behind the corruption of gems, it seems. That part appears to be safe to assume. Now, we also know that the diamonds called everyone to retreat.

We’re thinking that this is because the Homeworld gems were losing the war, hence the retreat. All Homeworld gems boarded their ships… except not all Homeworld gems actually evacuated in time. Centipeetle, her crew, and other gems did not board the ships in time, and were trapped on earth.

We don’t know what the white light was, except that it’s assumed to be what corrupted the gems, and was a weapon of the diamonds’ control. This presumably corrupted every gem left on Earth, making them into the monsters we’ve been seeing since episode one.

Now, one detail to cover is how the Crystal Gems managed to survive. We believe it’s because of Rose’s shield. We’re not sure exactly how strong her shield is, but it can be hypothesized that it would at least be strong enough to protect everyone within a certain radius.

We finished the episode five minute ago, so this is all thrown together hastily. Again, feel free to add onto this!