If it's a small enough ring try a small needle nose plier, or big use big POINTY needle nose, and screwdriver together. If you can get one end out of the groove get the screwdriver under it and keep moving around little by little. Maybe even find a donor screwdriver you can bend the tip of to help you pry.
Can surely be done, but as you found out it takes lots of patience. Careful pliers will also pinch your hand and cause blood blister(s). Have fun, KW