1. The rounder the better, it's best to put it on a horizontal glass, it will keep rolling by itself. Therefore, pearls are perfectly round.

2. The brighter the luster, the better, with rainbow-like halo, even.

There are many colors, the most common ones are white and milky white. There are few black pearls in freshwater cultured pearls, and roses, pink pearls and golden pearls are also precious.

4. The fewer flaws, the better. In the process of pearl growth, pits and protrusions are usually formed for various reasons, so the smoother the surface of a good pearl, the better.

5. The bigger the pearl particles, the better. Generally, it takes more than 5-6 years for cultured pearls to be harvested, and it takes more than 10 years.