Most of the rings can be resized and many jewelers offer this service. You may need to resize a ring to make it larger or smaller depending on the size of the ring and the size of your finger.
Jewelers will add extra material or stretch the ring’s shank to make it larger. Adding extra material will cost you some money. But it is the safest option not to damage your ring. But, stretching the ring’s shank may damage your ring. If done correctly, it is a cheap option.
To make a ring smaller, jewelers will cut a part of the ring’s shank and press and solder the two ends together. This may cause damage to the design of the ring. Also heating to solder the two ends may damage ring stones or gems.
You need to refer to an expert jeweler to resize your ring.
Resizing a ring depends on the ring thickness. Also design and setup of stones and how many sizes you need to change it, is very important.
To summarize, when a ring is resizable, it would be easy and cost-effective to resize that ring.