In any event it is best to be able to take rings off when you want, so let's see if we can get it off without any drastic action. Of course if you have already hurt your finger, and any attempt to remove the ring causes pain, you should get it cut off without delay. Sometimes a ring can be coaxed off without cutting it. Soak the finger in cold water, then use soap to make it slippery, and if you're lucky the ring will slide off. This method may work even if your finger is swollen, but don't keep trying if it causes discomfort.
People are often reluctant to have a ring cut off.
Normally it's best to visit your jeweller. He'll have a special saw for the job, which is easily done. Whilst we can't speak for other shops, we never charge for this service. I would recommend you contact your Hospital Casualty Dept., who also have the necessary tools. The tools available will damage the ring, and more seriously could injure your finger.