When buying piercing jewelry, it is important that you choose the right size for you. Which size you should get depends entirely on how the piercing is done, how your piercing sits, and what your anatomy looks like.
What you need to know is the thickness of the jewelry and length if it is a bar and inner diameter if it is a ring.
We often get asked what is a normal size, the customer says that we should take the most common for a specific piercing, but it's like asking us to guess what shoe size you have, size 38 is the most common shoe size for women but that doesn't mean that it fits everyone, or you...
Unfortunately, having the "healing jewelry" and wanting a smaller one doesn't help either, as there are no "standard sizes", not even when you're getting a piercing. All piercings are unique because all bodies are unique, what worked on your friend may not work on you.
Many people buy the smallest size they can find because they want the jewelry to be as tight as possible, this is the most common return handling issue we have, a customer who bought a ring in 0.8 x 6mm... it is extremely small and only fits a few piercings. The smallest size for you is not the same as the smallest size for someone else, even if you have the same piercing. To avoid unnecessary return costs, it is important that you measure your piercing so that you know what suits you.
The easiest way is to measure the jewelry you have in your piercing, then decide how many millimeters smaller or larger you want it and order accordingly. If you change the model of piercing, from a ring to a bar, for example, you will need to measure your body to know what to buy.
There are different ways to measure yourself so that you know what jewelry size you need, it depends on which part of the body/face it is. Google usually has good and explanatory images, type "How to measure...& name of the piercing" and search with google images and you will usually find help.
Ask a friend for help if you find it difficult to measure on your self. If you have the opportunity to go to a piercing studio, they will usually be happy to help you.