Most jewellers, especially those with a workshop on their premises, will have a piece of equipment just for this purpose. After the ring has been cut off, give your finger a week or so to get back to normal size before you have your finger measured and the ring made larger.
You may want to have that ring checked by a reputable jeweler. It sounds like you have a copper ring plated in white gold and the plating has worn off the underside and is oxidizing from the moisture on your finger. White gold is Regular gold mixed with a white metal like nickel to change its color.
It can be Rhodium plated to give it the appearance of white gold. However, over time this plating will wear off and the original yellow gold will begin to show through and you will have to get it re-plated. Contact your local jeweler for more information.
Yes it can ... this needs to be done at a jewelry shop - pretty standard thing for them to do and it doesn't hurt.
"18K" should be stamped on the inside of a ring band or near the clasp of a bracelet or necklace if it is 18 karat gold. No stamp may mean it is custume jewelry or the stamp may be worn off. A jeweler can authenticate a piece for you if you are unsure.
cut it off
There are a few types of rings that can not be cut off. Titanium and Tungsten Carbide are very difficult to cut off in an emergency situation.
If you're asking if it's really 10 karat gold ... do you think that someone who would make a ring of brass (or whatever) and try to pass it off as gold would be morally above counterfeiting a marking, or do you just think that would be too hard so they wouldn't bother?If you want to know for sure if your ring is "real" or not, take it to a jeweler for testing. Markings mean approximately nothing.
It means that it's cheap, not real gold or that the gold plating is so thin that it's wearing off.
Acetone
i would see a piercer
Platinum rings can absolutely be cut off. The only metal you have to worry about not being to cut off is titanium or tungsten. They can be cut off in emergency situations, but your local jewelry may not have the tools to cut them off. In some circumstances, you may have to visit the local hospital or firehall, as those institutions usually have the tools necessary to help you out. In the case of platinum, however, your jeweler should be able to cut it off without a problem.
Probably the cheapest, most effective method would be to wash your hands in running water just as cold as you can possibly stand. Make sure to use plenty of soap, in particular on the ring finger. As your fingers get colder, they will begin to constrict. Likewise, by working the soap (liquid, non-foaming would be best) on and around your ring, you'll be lubricating the ring. At this point, with minimal effort, you should be able to pull the ring past your knuckle, and it should be a fairly simple process from that point. Another method is to slide a string under the ring. Then wrap it as tightly as you can around the finger headed toward the end and over the knuckle. By pulling the string under the finger it will slowly move the ring up the finger and over the knuckle. Be careful! You may want to consider going to a jeweler's and having them cut it off as a safer way of removal.