Determine ring size 

To measure your ring size exactly, it is best to visit the jeweler. They can measure your ring size for you for free. 

A handy way to determine the size of your ring yourself is to measure the circumference of your finger. All you need for this is a ribbon or string. Place this around the finger you want to measure, making sure you don't pull the ribbon or string too tight. Then place this along a measuring tape or ruler and determine the number of millimeters. If you cannot arrive at a standard size, choose the nearest (larger) size from the table. You can of course also read the inside size of a ring that you often wear by holding it next to a measuring tape or ruler. When determining size, keep in mind that the ring must fit over the knuckle.

 
Determine bracelet size  

A handy way to determine the size of your bracelet yourself is to measure the circumference of your wrist. All you need for this is a ribbon or string. Place this around your wrist, just behind the lump, making sure not to stretch it too much. Then place the ribbon or string along a measuring tape or ruler and determine the number of centimeters. If you cannot arrive at a standard size, choose the nearest (larger) size. 

Tight bracelet        Wrist size + 1/1.5 cm 
Normal bracelet      Wrist size + 2 cm 
Loose bracelet           Wrist size + 3 cm