1. Jewelry is generally made of metal, which can reflect light. Black gloves can absorb light and prevent the reflection of hand light from interfering with customers' observation of jewelry, thus affecting customers' perception of jewelry luster.

2. Jewelry is usually small and rich in details. If hand sweat sticks to jewelry, it may affect the luster of jewelry, and even some jewelry will be corroded, and black gloves can effectively avoid this problem.

Black is considered as a symbol of elegance and professionalism. When selling jewelry, black gloves can enhance the professional image and win the trust of customers.

To sum up, wearing a left-handed black gloves when selling jewelry can not only enhance the professional image of sales, but also ensure the quality of jewelry and give customers the best shopping experience.