Determine ring size 

A handy way to determine the size of your ring yourself is to measure the circumference of your finger. All you need is a ribbon or string. Place it around the finger you want to measure, make sure you don't pull the ribbon or string too tight. Then place it along a tape measure or ruler and determine the number of millimeters. If you do not arrive at a standard size, choose the nearest (larger) size from the table. Of course, you can also read the inner size of a ring that you wear often by holding it next to a tape measure or ruler. When determining the 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 is a ribbon or string. Place it around your wrist, just behind the lump, making sure not to stretch it too much. Then lay the ribbon or string along a tape measure or ruler and determine the number of centimeters. If you do not 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