I mean, this would be default.
Honestly, though, you might not even see signs of an endoskeleton like this.
Though people say that gems look like humans, that'd be unlikely, and not just because they're aliens.
Remember when gems form? What do you see first?
They look like articulated dolls. That would be their true internal structure, so no defined ribs or collarbones.
As a matter of fact, I imagine realistic gems would look kind of unsettling.
Probably rubber pulled over that doll form. After all, why would they have residual hair? Besides their head and eyebrows, they're probably completely hairless and blemish free.
It'd be an uncanny valley thing.