Any growth larger than an eraser should be removed is a general rule. Not all moles are dark, there are skin color moles, there are red moles and the most common ones which are dark. In any case you should consult to see if your mole can be removed without doing a biopsy.
There are indicators of malignancy and they follow a rule. A=asymmetry, B=borders, C=color, D=diameter, E=evolving or growing size.