AAA grade: The whole crystal is transparent and flawless inside and outside, and the surface has no man-made defects visible to the naked eye.

AA level: there are tiny flaws, or tiny natural inclusions, clouds or flocs not exceeding 3mm.

Grade A: There are slight defects, and clouds or cotton wool can be easily seen by naked eyes.

Class AB: There are big cloud inclusions, small ice cracks and small scratches on the surface.

Grade B: More than half of the whole crystal is cloud-like and inclusion, with large ice cracks and small cracks on the surface.

Grade C: the lowest grade, cloud-shaped, with obvious ice crack marks and obvious cracks on the surface, which seems to be broken at any time.

This is only a distinction between businesses, not a level recognized by the state. It's just convenient to distinguish. The identification center only identifies the true and false. Generally speaking, the higher the purity of the crystal, the greater the value.