Some certificates issued by formal appraisal institutes cannot detect seawater or freshwater pearls, whether dyed or undyed, because these appraisal institutes not only do pearl appraisal, but also mainly do other jewelry, jade, diamonds and so on. They can only tell whether pearls are real pearls, not whether they are dyed or undyed.

As can be seen from the above appraisal certificate, only the appraisal result is pearl necklace or pearl, not seawater or fresh water, not to mention size, luster and so on, so there will be a problem that customers buy real pearls with certificates but still dye them.