Why is my gum not pinkish in colour? it is quite dark like purple. im not smoking

Dark Gums: It may be the natural color of your gums if you have a dark complection. More than likely it can be inflammation from gum disease. If you haven't had a dental examination and a cleaning recently i suggest you schedule to get it checked. A third possibility is that it is associated with some sort of pathology. The only way to know is to have a thorough exam and diagnosis with your dentist.

Melanin : Can be acquired genetically and can make gums look dark. A dentist can be able to distinguish whether the purple discoloration is caused by gum disease or merely a melanin.