Diamond Jim's is the perfect jewelry store. The staff is knowledgeable, friendly, and accessible, and the quality of the merchandise is excellent. Whether you want to buy a piece of jewelry for $50 or $500 (and I've done both at Jim's), you will get the best value for the money you spend and the staff will listen to your needs and work to get you to find the perfect item within your budget.
A good jeweler is like a good mechanic: once you find him, you won't trust going to anyone else. Jim is always gracious and friendly. He is supremely knowledgeable both about his inventory and the industry generally. When I have sold pieces to him, he has always given me the best price around, whether its gems, gold, or watches. Jim is always open to a conversation about price and will work with you to get to a place where everyone is happy. I most highly recommend Diamond Jim's.