Here are a list of reasons:
1. One thing is for sure, it is easy to set up an online store.
2. Jewelry is a very diverse commodity (earrings, necklaces, wristwatches, bracelets, pendants, rings, etc.).
3. Precious jewelry does not lose much value and can be resold.
4. The profit margins are huge, depending on what you are making and selling.
5. Shipping is streamlined and secure and cost very little to ship jewelry.
6. It is easy to manage an online store.
There are hundreds of designers who make and sell their jewelry online - earning a steady monthly income. The profits often get much bigger around the holiday season when people spend much more money.
The best part is that since there is so much variety in jewelry, you can choose a specific style and focus your efforts on selling that. Or, you can select several styles and go for it!
No matter what you make and sell online, enjoy the process. It will show in your work.