How can I convince my mom, who is a violin teacher, to let me grow my nails out this summer for a dance?

My mom makes me play the violin, and because of that, she always makes me keep my nails cut. (In case you don't play, you need to have short nails to pluck and do vibrato.) This summer, there is going to be a dance at my school that's going to be pretty fancy and I want to grow my nails out for it so I can get a manicure and have nice nails for once. It's the perfect time, too, since school is out, and I won't have to be in orchestra playing for important stuff. She didn't even let me grow my nails out for prom, so I had to go to prom with short stubby nails. I've tried reasoning with my mom, telling her how I won't have orchestra, but she still won't let me. She says that she is still going to make me practice, and since I will be practicing, I have to do it the "right way," which means with my nails cut. What else can I tell her to make her change her mind?