"What about - Oh, of course!" Pearl's cheeks were tinged slightly with blue as she realized she hadn't explained herself to Ten. "I'm a Gem. It's... A little complicated, really, but essentially: this - " She pointed to the Gem on her forehead. " - is me. The rest is an illusion, although of course, this form has actual mass, and such. I'm from the Gem Homeworld, though I've spent hundreds of years on Earth."