Amy is mad at Sheldon, and he goes to the jewelry store with Penny to buy Amy something. Sheldon hints to the salesperson that diamonds are carbon just like charcoal, but it's only their molecular arrangement that makes them valuable. When the salesperson tells Sheldon that everything is on sale, Sheldon is suddenly more interested in a pocket watch he was previously considering.

Jerry is getting a new air conditioning unit. Elaine asks why, because he's never wanted air conditioning before. But Jerry's new girlfriend feels more comfortable in with air conditioning, so Jerry is getting one—his demand has increased.

Richard heads to Peter Gregory to pick up his check but isn't prepared with all the necessary business documents for his startup.

When a product is in high demand, a manufacturer is obligated to charge a little more to pay back the investors who took a risk on the product. Watch Warren Buffett’s Secret Millionaires Club on the Kid Genius channel on Xfinity. Visit SMCKIDS.COM for webisodes, comics, games, and more!

When Sheldon alerts Penny that she'll earn over $3,000 for a single night of work, she imemdiately goes to buy shoes.