I don't know if there is a jewelry appraisal office over there. You can go with the merchants to make an appraisal to determine the authenticity.
Let's see if there are any natural textures first. Some red corals are delicate in texture. It is ok to look at them with a magnifying glass, which is generally visible to the naked eye. If there is no false texture. Judging from the texture, it may be dyed by sea bamboo and white coral. Dip it in water or acetone to see if the color will fade. If the sea bamboo is dyed, the texture is unusually large, thicker than the fingerprint, and the red color is dull and lifeless.
Good luck ~