There are ring cutters to cut rings off fingers with and there are ring cutters used by jewellers to size down a ring. Ring cutters used for cutting rings off fingers are not used with the intent of preserving the ring so much as freeing the finger from the ring. The ring cutter used by jewellers is all about preserving the ring at all costs. The cutting is handled with deliberate care and the ring is resoldered and sized according to the customer's order.
Use an electric ring cutter in an emergency such as when the hand is swelling badly, cutting off blood circulation. Slip the blade guard between the band of the ring and the finger. Turn on the cutting tool and press the blade into the metal until it's cut all the way through.
Use a combination manual-electric ring cutter to cut a ring off a finger that's got stuck so badly that not even lubricating the skin with soap will get the ring to come off. If there is no urgency to getting the ring cut off, use the cutter manually. Slip the blade guard in between the ring and the finger to protect the skin. Then simply turn the butterfly key to rotate the blade which will slowly cut a little deeper into the band of the ring with each turn of the key. If removal is urgent (pain or swelling in the finger is present), replace the butterfly key with a specially designed hexagonal key that is included. Put a hex bit---a six-sided, flat-tipped bit---into a cordless, electric screwdriver. Insert the bit into the hex key and turn on the cordless drill. Suddenly the manual ring cutter becomes a fast-cutting electric ring cutter.
Use traditional ring cutting pliers, which are manually operated, where time is not of the essence or if it is but there is no alternative to getting the ring off faster. Slip the blade guard between the ring band and the finger and manually turn the butterfly key to turn the cutting blade.
Position the ring into the ring cutter's clamp, with the bottom of the ring shank facing up.
Choose the cutting die that is equal in size to the amount of metal to be removed and lock it into the ring cutter.
Pull the handle down to cut out the exact amount of metal to be removed to make the ring shank smaller. Tap the remaining ring band together on a ring mandrel---a long cone-shaped steel rod used for making a ring perfectly round---and solder the ring shank back together.
Do not use an electric drill in place of a cordless screwdriver when using an combination manual-electric ring cutter.