There are a large variety of ways to go about selling your jewelry online. My focus will be on low to no cost ways to sell items. Of coarse blogs will be a free way to start your online jewelry business.
You can start with a blog and upgrade when and if you start to sell your items. Of coarse if you find that your blog meets your needs you might not want to progress further than that. Because your blog is free your costs of running your business will probably only include the cost of PayPal when your items sell.
Some free blogs:
Blogger - http://www.blogger.com/
WordPress.com - http://wordpress.com/
Live Journal - http://www.livejournal.com/
Blogs4me.com - http://www.blogs4me.com/
Blog.com - http://blog.com/
This site has over 40 providers of blogs:
40+free blog hosts -- http://mashable.com/2007/08/06/free-blog-hosts/
PayPal - As long as you have a PayPal account that is a merchants account you can put PayPal buttons or shopping carts on a blog site with no problems. Establishing a merchants account is not difficult. It just involves confirming your bank account and linking your PayPal account with your bank account. PayPal does a great job of explaining the how-to's