Gums dark purple color may be caused by normal physiological reasons, but it can not be ruled out that it is caused by gingivitis, wearing metal crowns in the mouth, and so on. You should consult a doctor in time to find out the cause of the disease. 1. Physiological reasons: due to the pigmentation of the oral mucosa itself, the gums will appear purple, if there is no pain, redness and swelling and other symptoms, is considered a normal physiological phenomenon, do not need special treatment. 2. Gingivitis: If you suffer from gingivitis, due to the stimulation of inflammation, it will lead to pigmentation of the gums, dark purple, usually accompanied by the phenomenon of bleeding gums. 3. Metal crowns in the mouth: If the patient has metal crowns in the mouth, the metal is corroded by saliva, due to the ionization reaction precipitation, will be deposited in the gums, resulting in purple gums. There may be other reasons for the purple color of the gums, it is recommended that the patient consult a doctor in a timely manner to clarify the specific causes, and if necessary, to carry out the appropriate treatment.