When the design doesn't dictate the shape, oval jumprings are often used when you want a charm or element to be less likely to come free from another link. When working with round jumprings, the seam could be at the connection to another jumpring and offer the chance of coming separated. Oval jumpring seams are always on the side rather than at the top or bottom. This offers a reduced chance for the jumpring to become separated from the connecting links.
- Molly Schaller, Jewelry-Making Expert