Pacific Silverworks offers a Sterling Silver Donut Hinged Bail.  Perfect for your donut problem, this component is hinged at the bottom for ease of use and finishes off your donut so much better than the usual looped leather or cord. It also has slightly oval rings for putting a chain through. 27mm x 4mm

Also available in Gold 

Comes in a smaller size, 21mm x 4mm for smaller donuts.