I'm not sure I have a full grasp on the situation, or how the other person is using your jewellery, but AFAIK, original designs are protected by copyright (if you can prove they're original and yours), so if she is using your pieces and making / selling them herself, you could have some recourse there (and if she has made / sold any copies, you may be entitled to a portion of the profits if you can prove yourself the copyright holder of the designs). She would be misrepresenting your (and her) work if she is using images of other people's work to advertise her business, but I don't know enough about what can be done officially to give any advice other than recommending that you consult a legal professional. 

Copyright issues aside, if she owes you money or still has items and won't cough them up, small claims court may be an option to try and get any money owing for pieces that were sold.