I'm cooler on the "era 2 Lapis" theory after looking it over again. Besides the body being completely different, I don't think the wings are made of water—they're mostly translucent, but have irregular sections of opacity, like some gemstones have.
I doubt the Diamonds will be CMs at this point. Their love for each other seems to be genuine. If any of them WERE a CM, they would have to be an utterly selfish bitch who would backstab their sisters with no regrets.
Speaking of mysterious gem silhouettes, the smaller mystery gem in the latest trailer, kinda reminds me of a Smoochum (except the wings, of course).
Also, the blockier other gem from the same trailer. Maybe it could be the first male-appearing gem in the series, excluding Steven?
The Superstar of the Supernatural World! (debatable)Gems don't act ambiguous enough, so that first thing could potentially work for a fan made story....
Because officially they have no reason to address those concepts in-universe.
Steven Universe.
Rules of the Internet 45. Rule 45 is a lie. Check out my art if you notice.![]()
I mean, Jasper's probably the most masculine that any gem ever has been or ever will be and she still identifies as female.

How would Steven react to such a villain?
And do you think a CM would evoke Even Evil Has Standards on behalf of the Homeworld Gems?