1. Definition: A diamond dealer refers to a middleman who has the right to view and buy diamonds directly from diamond producers or wholesalers. A picker refers to a retailer or jeweler who buys diamonds from diamond retailers or other middlemen.

2. Functions: The main duties of diamond inspectors are to provide high-quality diamonds to their customers (such as jewelers and retailers) and ensure that their customers get the best price and service. The main duty of commodity selector is to choose the right diamond according to the customer's needs and tastes, and make it into jewelry or other diamond products to meet the market demand.