Trade for a diamond? How the hell was Tris supposed to do that? She'd never had enough money to afford even cubic zirconia, how was she supposed to get a diamond? Tris wasn't even socially confident, why did she have to talk to Thatcher when Shark already knew the guy? Tris was growing really sick of Shark's requests but at this point she'd do anything to get the boat fixed.
A few hours later Tris strutted along the beach front, she had a plan. All this Thatcher guy wanted was to appease the 'crab gods' right? And you know what crabs love? Bacon. They go crazy for the stuff. Honestly, dump a little bit amongst crab filled rocks and they'll be crawling all over the stuff in seconds. Tris felt confident, if she could prove to Thatcher that the 'gods' preferred her 'offering' to his then maybe just maybe he'd give her the gemstone Shark was after.
"Hey," Tris greeted Carter, they'd only known each other a few days and Tris had been bringing him any vaguely gemstone shaped objects she'd been finding. He'd been unimpressed so far, she'd mostly been bringing him seaglass and other worthless bits, but hopefully she finally had something to offer. 
"What have you got now?" Carter raised an eyebrow sarcastically, wondering why this random kalon wouldn't stop bringing him junk.
"Look Carter, this will sound crazy but I think I have something the crabs will want more than that diamond you've got there. I'll prove it." Tris threw a small sliver of bacon into a nearby rockpool. Immediately, hundreds of crabs were crawling around snapping at the food.
"Whoa kid! Impressive! The gods love you! Here take today's haul, I'm sure you can find a good use for it.
Tris took the diamond and other gemstones back to Shark. She couldn't wait to get back home to her work.
(315 words)