Start a blog under your existing domain name. Contact your webmaster and ask about options to place a blog within the same domain as your business. For example, if your website sells topaz is called jewel-jewel.com, then the domain of the blog should be something like jewel-jewel.com/topaz-blog.

I recommend:  From my experience having used many blogging platforms, I am partial to the Wordpress platform. Wordpress gives you many useful plug-ins allowing you to integrate various tools, for example it lets you upload your photos directly from flickr onto the blog, and well as many useful search engine optimization plug ins which will help to improve the visibility of the blog.

Carefully craft your blogging style using an honest approach. People will never trust you if your blog is all about self-promotion. You need to have an honest approach to your blog including information from and linking to a wide variety of resources. When writing use a natural tone and remember to prioritize interesting topics over topics which simply suit your store. The blog should stand on its own merit, and only link to your products where natural and appropriate. Don't be afraid to write about other bloggers and start a relationship with them to further increase visibility of your blog and create interaction in your blogging community.

I recommend:  To find other existing blogs about your topic, or view other blogs for examples Technorati is a great resource:

I also recommend setting up "google alerts" to keep track of who is writing about you. You can set the alert for any term (for example your brand name) to notify you any time the term is used. This is a good way to track the publicity about your brand and make sure that your blogging interaction is on track.

Increase interest, increase traffic. Increasing interest in your blog will ultimately lead to more traffic through both referrals and through search engines. Most bloggers find it difficult to consistently develop fresh and interesting content. Be creative! Maybe your supplier has a unique or interesting experience, or you found an article in the news that you can editorially comment about. Most importantly remember your audience and think about what interests them!

I recommend:  A great place to find contributors to jewelry blogs are flickr's jewelry groups. Look for people who are designing or photographing jewelry. Most of them would be happy to contribute to your blog in exchange for some exposure to their designs. This is also a good place to find a business contributor, supplier etc!
One way to sidestep your writers block is to introduce guest contributors who share your passion for jewelry or publish interviews with designers.

Many jewelry forums are a good place to find examples of interesting topics and conversations.