1. Organic gems: mainly refer to pearls, corals, amber, beeswax, ivory, etc. Organic gemstones contain organic components, most of which are not high in hardness, so as to avoid bumping and falling. Therefore, it is necessary to avoid using ultrasonic to clean pearls, which is easy to scratch and seriously damage pearl jewelry.

2. Gems: mainly refer to colored gems, such as rubies, sapphires, tourmalines, emeralds and garnets. Because all kinds of gems have different hardness, those with high hardness can be cleaned by ultrasonic cleaning machine. Emerald, tourmaline and some gems with many inclusions, cracks, brittleness and low hardness should not be cleaned by ultrasonic machine to avoid damage or fragmentation.