1. Low cost: Joy jewelry may adopt low-cost manufacturing methods, such as using cheaper metals, gems and crystals instead of more expensive materials. In addition, its design may be relatively simple, without a lot of manual labor, further reducing the manufacturing cost.

2. Market positioning: Joy Jewelry may be positioned in price-sensitive markets, such as online or specific areas. In such a market environment, price advantage may be more valued than brand awareness or product quality.

3. Operational efficiency: Jiuyi Jewelry may adopt efficient strategies in both production and sales, such as using more efficient supply chain and sales channels, thus reducing the overall operating costs.

Generally speaking, Joy jewelry is cheap mainly because of its proper cost control, positioning in the price-sensitive market and efficient operation.