Helping Girls Deal with Bullying
It is appropriate for you to speak to her teacher about the bullying (because that is definitely what it is) that your daughter is experiencing. It is unlikely that the girls will stop without adult intervention, and it could begin to affect your daughter's feelings about herself. You need to follow through and make sure that something is done to stop the behavior. By standing up for her rights, you will give her the message that you are proud of her and the way she looks and that you won't tolerate anyone treating her otherwise.
In addition, you can give her a response to say back to the bullies instead of ignoring them: "Your mean words make you ugly." Although this may not stop their behavior, it will empower your daughter to stand up for herself, and self-confidence is an important part of feeling beautiful.