Is a two colored mole pr definition melanoma?

Never that simple: Melanoma is a cancer of the skin that has many features including multiple colors ( usually more than two), irregular borders, recent change in size or shape and many other features. Two colors alone is not sufficient proof. Do you have a family history ? If there is concern, seek out a physician for biopsy if needed. This simple procedure will save you a lot of anxiety, if needed.

Mole : Abnormal moles and melanoma skin cancer often have two or more tones (brown, black, red) or are very dark . Have a dermatologist evaluate and treat any suspicious mole.

It's complicated: Any suspicious mole should be checked by your doctor. Moles with multiple colors are surely more suspicious for melanoma, but not definitive. On the other hand, some melanomas have no pigmentation, making them much harder to diagnose.

No: It would not be definitely melanoma, but it does raise suspicion. You should show this skin lesion to your friendly dermatologist.