The ring gauge will enable you to find out the size of a ring, so you can know the size of your finger, or that of the person you want to give a gift to. We've created a PDF document that you can print out in actual size. To do this, check the length of the segment on the printed sheet, which must be precisely 10 centimetres long.
All you have to do now is apply a ring that suits you to the different circles, until you find the right one. The right one is the one you can see inside the ring, without seeing a gap between the circle and the ring. You should also be aware that there is very little difference between 2 successive sizes, sizes 52 and 53 being virtually identical, the finger being able to adapt to 1 mm of difference.
If you hesitate between 2 sizes, choose the larger one.