After watching "Keep Beach City Weird" near the end where Ronaldo regains his weird thirst and by what he says I made this theory.

Ronaldo says the diamond mean "Polymorphic Sentian Rocks", which bummer for him, are what gems are... Sometimes it's just sad how these things happen.

But no fear because with this evidence we can say The Crystal Gems (or gems in general) are known worldwide. Maybe the president was a gem, or in particular Diamond. This one statement could make several theories arise but I won't go too deep.

{Unless you want me too, because I can!}