1, opal, pearl, emerald, Tanzanian zoisite, malachite, emerald, lapis lazuli and coral.

2, organic gemstones, opals, turquoise, emeralds.

3, borderless and micro-inlaid jewelry can not be cleaned with ultrasonic cleaning machine to prevent the gems on the jewelry from falling off.

Generally speaking, pearl ornaments and jade articles can't be cleaned by ultrasonic wave, nor can gems with serious cracks be cleaned by ultrasonic wave.