Just had to add that I have Dave's KoilKutter too and love it. I"ve been using it for just over a year. My jump rings are primarily 16 g sterling wire with a 5 mm diameter. It works perfectly. I probably don't cut as many as most full time jewellerys but - maybe 200 a month- but I"m still on my first blade!!!! (its near the end though)

Love that gizmo. Sure beats sawing them. I also used to use the dremel with a diamond blade but I wasn't happy with the results.