Are Gems Artificial?

Firstly, to be clear, gems are obviously NOT organic, but that doesn't mean they're necessarily *unnatural*. A lot of discussion seems to stem from the assumption that the Diamonds were created by someone for a purpose. But what if that's not true? Could the Diamonds have been formed through natural, but unlikely circumstances?

While some outside information from the creator and crew seem to imply that the Diamonds were created, is there actually any in-universe evidence of this? The lower gems are certainly more akin to computers, but the Diamonds, especially pink seem far more... natural. Natural enough to heal the organic, and eventually become one with them.