I share this experience with you in an attempt to help you cope with this frustrating event in the most positive way I know.
From the first time a cave dweller made a mark on the wall with a piece of charcoal, I have a feeling there has been this claim of "She's copying me!"

When I made jewelry full time, I was widely and blatantly copied. Each time I realized my work was being duplicated, I moved on to learn a new technique, try a new method and experiment with a different style. I didn't waste time and energy lamenting that someone was trying to copy me. It forced me to become a much more accomplished artist.
If I had never had competition, I would still be living in a small townhouse in Virginia Beach, working two jobs and making Friendly Plastic jewelry. Those of you who realize the value of competition, rise above the masses and go on to accomplish all that you are capable of. I am grateful for those women who came to every show, went through my trash trying to find out where I bought something and stood in front of display cases in boutiques taking notes.
Today I employee several people and help to sustain many small businesses and families. In part, I credit my success to those early copy-cats who forced me to learn more.
If you find that a designer has made something similar to your work and then prices it below your fair-market price, keep in mind that underpricing the items you make, can and will put you out of business very quickly. When you don't factor in enough profit to replenish your supplies and pay yourself at least a little for your time and creative energy, you will not continue to make and sell jewelry.
There are legal steps you can take to stop people from copying you.
This paraphrased information is shared with us by Willie Zuniga.
Have you ever wondered why people add the "YourNameHere ©2009" statement at the end of every page? That is exactly what you are supposed to do. It states your intent to claim copyright, and will prevent people from assuming it's all right to copy your work.
When your item is "published," (magazine, book, Internet, photo) you automatically have limited protection simply by adding your copyright statement. If you ever have to go to court though, you need to have a registered copyright in order to collect monetary damages.
There are certain conditions that apply to jewelry, and frankly a lot of it won't be accepted. There has to be a "creative use of the medium," for example, simply gluing a cabochon into a setting isn't going to pass as something you can copyright. But most of the wrapped, layered, detailed jewelry will ... if not as jewelry then as sculpture. You can apply for a copyright once every six months. The cost ranges from $35-50, and often a collection of related items can be registered for a single fee.