Not sure about the size ring? Here's an easy way to find it at home:

Step 1: Wrap a thread around the base of your finger (not too tight, not too loose).

Step 2: Use a pen to mark the point where the thread overlaps.

Step 3: Unwrap the thread and measure the length between the start and the mark, in millimeters. 

The size you select on the website corresponds directly to the circumference of your finger in millimeters.

For example, il you measure your finger and get 52 mm, then your ring size is 52.

Use this chart to help you :