"Nice to meet you. Welcome to the Jewel Appraiser J's store. I appraise gemstones all around the place, and I will buy it if I like it. The more rare the gem, the more money I will give."
"If you have any gemstones, would you like them appraised?"
"I see. If you ever find any gemstones, feel free to come to my store."
(If the protagonist gives him the Unpolished Stone) "Excuse me for a second. I'll appraise it now. Hmm. Interesting... Let's see...let me see here..."
"This must be...a Turkish stone! Otherwise known as Turquoise, characterised by it's bluish colour. It is believed to bring happiness to those who have it. Well, let me buy this from you."
"Hm... Well... This must be...an Emerald. Once it was believed that an emerald was given to Venus, the goddess of beauty. A deep and glamorous green stone. It was believed to be a sign of the sincerity of one's love amongst lovers. How romantic, isn't it? I love this stone. Well, let me buy this from you."