After cleaning the aging part of the surface of the fish essence, cement the fish essence, and then use sandpaper as a polishing tool to remove impurities and cracks on the surface and polish the shape of the fish essence into a regular shape (pay attention to the problem of friction and heat generation during polishing to avoid new cracks in the fish essence). Finally, the fish essence is refined, finely ground and polished.
Herring stone, also known as fish essence stone, fish shock stone, black pomfret stone and fish pillow stone, is the throat under the pillow of herring and is used to help crush the horniness of hard objects such as snails. Yellow and tender in color, shaped like a heart, hard as stone after drying and crystal clear as jade, it is a treasure in Hakka area. Other common fish do not have this kind of stone, so it is rare and precious. After herring stone is naturally dried, the material is stable and can be stored for a long time.