Approximately 2" x 1.5"
You have a Japanese Ivory pendant marked Meiren most likely with gold setting. Usually gold is marked. Otherwise I would recommend asking a jewelry store to test it. The pendant is made around 1920 and that is concerning CITES regulation ( elephant ivory must be worked before march 1947 ) old enough to sell it legally if you would like to do that. Depiction is Shou Lao the Chinese and Japanese god of long life and happiness. The pendant is interesting and well mad. If you would like to sell I recommend an auction house with a prescription to an online platform like Invaluable, live-auctioneers or other. That way you are sure there is a good international audience for it.