Have I got a deal for you!

Yesterday, we found out that within the resort town of Ur, they use money, a coin specifically, as a medium of exchange. The name of the coin is a Deucat and it has a picture of The Hand of Deucado on one side and an image of the planet of Deucado on the other. The size, weight and composition was very similar to a silver dollar, a Morgan Dollar actually (example below). Since this was the first time they ever encountered one, clearly Rome and Rei did not have any. Rei needed to figure out how to get some:

     Rei handed the Deucat back to the merchant and turned to Rome.
     “Let me have your ring,” he said.
     Rome quickly hid her left hand behind her back. “Why?” she asked suspiciously.
     “I just need to borrow it for a few minutes,” Rei insisted. “I’ll give it back, I promise.”
     “Very well,” Rome said unenthusiastically. She used her right hand to gently twist and remove the diamond engagement ring off of her left ring finger. The ring had been Rei’s gift to her on their one year anniversary. It was among her most prized possessions because of what it represented. Reluctantly, she handed the ring to her husband.
     Rei held the ring out to the merchant. “How much will you give me for this ring?” he asked.
     “Rei!” Rome shouted. “No!”
     “It’s OK,” Rome,” he said. “I know what I’m doing.” The merchant took the ring from him and held it up to the light.
     “It’s a four carat flawless diamond with two one-carat diamonds on the sides. Mounted on a pure platinum base.”
     The merchant’s eyes grew wide. “This ring, it is very valuable,” he said. “I would nawt have enough to pay ya. Maybe up top? At the casino?”
     “Not necessary,” Rei said. “Would you say that ten Deucats is a fair price?”
     “Ten Deucats?” the merchant sputtered. “It is worth a hundr’d times that much, a thous’nd.”
     “OK then,” Rei said. “I’ll sell it to you for two Deucats.”
     “Rei?” Rome whined, “what are you doing?”
     “Shhh,” Rei chastised. “Two Deucats?” he asked again.
     “Of course, of course,” the merchant said. He reached into his bag and pulled out two silver coins.
     “So here’s the deal,” Rei said. “You’re giving me two Deucats. I’m going to go away for a little bit and when I come back, I’ll give you ten Deucats to buy the ring back. The way you said. OK?”
     The merchant narrowed his eyes.
     “Look, you’re making back five times your investment in just a few minutes. You agreed it was worth at least ten Deucats. Do we have a deal?”
     “Ya,” said the merchant. “We can do this.”
     “Great,” Rei said and he held out his palm. The merchant dropped two silver coins into his open hand.
     Rei turned to Rome and Bonnie. “I’m going to go down the road for a few minutes. You two stay here and keep an eye on this guy. Make sure he doesn’t do anything funny or take off.”

Hmm. The world of Deucado has unlimited energy and molecular sequencers. A person can literally have anything they want. Rei wants some Deucats. What do you think he's going to do with his sample?