Ive had my ear pierced for so long. but mum doesnt let me wear it with her?

im 16. i got my left ear pierced around a year or 2 ago. without her permision and she got mad. but she got over it after. but yet she never lets me wear it when im with her, only when im out with friends and stuff. she says my diamond is too big, and that she prefers small ones. ive got a very small one and i ask to let me wear and then she still says no :S. and it jus pisses me off so much. because when she sees players like ronaldo, she thinks hes gawjuss and stuff, but yet dont let me wear my earings with her!!. any one help me with a way to persuade? pleaseeeeee this is so annoying