Wearing a single pair or not means that the beads on the bracelet are odd, not even. This is an old saying, which is out of fashion now, and crystal bracelets can be worn casually.

Introduction to Crystal:

Crystal is a rare mineral, a kind of gem, and a kind of timely crystal, which belongs to the timely family in mineralogy. Its main chemical composition is silicon dioxide, and its chemical formula is SiO2. When it is pure, it forms colorless and transparent crystals, and when it contains trace elements such as aluminum and iron, it is purple, yellow and brown. After irradiation, trace elements form different types of color centers and produce different colors, such as purple, yellow, brown and pink. Inclusion crystals contain associated inclusion minerals, such as hair crystal, green ghost, red rabbit hair, etc. Inclusions include rutile, tourmaline, actinolite, mica and chlorite.