How to deal with annoying girls in cl who makes me feel bad about myself all the time?..Help please?

I am originally russian and have lived in USA about 6 years. Im 25 years old and go to UT Fine arts major in texas. I have this problem recently with some of my clmates and they make me feel so bad.. They are all those type of rich/fashion girls who care about who iswearing what and make comment on everyone alot.. As they have found out im russian due to my tight accent( which i really cant do anything with it) they have t=started being rude to me and make fun at my accent and even the way i wear( very simple minimal) allthe time in the cl in front of evryone.. Well its ART cl and we are free to talk loud and speak during work.. I am very respectful to everyone. Ive never disrespect anyone even if i have been insulted but this just getting to much.. Being their clowns all the time to laugh at me. I dont speak alot and i say when i need to say something but they just keep talking behinde me and make faces behind me in the cl when i start taking.. Thta is making me feel so insecure.. I know i shouldnt be this sensetive but its just hard to deal with them.. once i told them hey what is the problem and they said "your accent is the problem , hahaha! ." Im beautifull and smart and i love myself.. just feeling bad sometimes because of these people who annoy me.. I need seruois advise please. Iam NOT going to ***** them back just wnat to know how to deal or what to tell them to get them shup up in polite way.. Thank you..