Sometimes you have a ring that is too loose to wear. If you don't want to get it permanently resized to a smaller size but you need it tighter to wear comfortably, there are some simple options available to you. You can purchase commercial ring adjusters, but if you don't want to spend the money or don't have to the time to find or order one, you can tighten a ring with materials you have around the house.
Take about three inches of scotch tape and fold it lengthwise, sticky side out. Wrap it around the inside of the ring, adding layers as needed to create the desired fit. Cut away any excess tape.
Take yarn and wrap it around your finger. Test the ring for fit over every few loops of the yarn, until you have achieved the desired size. Cut away any excess yarn and tuck the loose end under the yarn loops on your finger.
Consider wearing the ring on a ribbon around your neck until you can get it sized. Although that does mean it won't be on your finger, there is security in knowing the ring is safely tied around your neck.
Warning
Be careful when wrapping yarn around your finger that you not wrap it so tightly that you lose circulation.