The Wall Street Journal recently wrote an article about intellectual property protection as it relates to the fashion industry.
There are a few things to keep in mind when fashion and IP law intersect. First, you cannot copyright a fashion design in the United States. The reason is that copyright does not extend to functional things such as clothing. The fashion industry has tried for years to amend the copyright act but so far they have not been successful. You can however trademark a distinctive design that consumers associate with a particular company. A good example of this is the Burberry plaid design. The Burberry design is protected, not because a copy might damage the creative expression of Burberry, but instead to protect consumers from being confused as to the source of a competing clothier.
Jewelry is another matter. Jewelry designs can be protected by copyright and knockoffs are quite prevalent in this area so it is a good idea to constantly register new jewelry designs so that any copyright claim can be enforced.