Mess with her mind

You take out the sapphire gem. "Ariel cannot see me. She will start masturbating withe one hand and roughly fondling her boobs with another. She cannot stop," you think.

Ariel opens her eyes. She slides her right hand down into her bikini bottoms and starts squeezing her right breast with her left hand. "What the fuck?" she mutters. The more she continues, the more freaked out. "What's going on?" she mutters. She looks around and starts breathing heavily.

You take out your phone and start filming her. With your free hand, you grasp the blue gem. "This is making Ariel hornier and hornier, but she can't orgasm. She will bring herself to the edge of orgasm, but not be able to get herself over."

"Oh god, what's happening?" asks Ariel.

You continue. "Ariel is fantasizing about a stranger fucking her up the ass in her pool. She can't get this fantasy out of her head."

Ariel starts fingering herself faster and deeper. "Oh god! Oh fuck! Oh god! Oh fuck!"