The most reliable way to determine your correct ring size is to visit a jewelry store and have it measured with a ring mandrel. Otherwise, you can click on the following link "Ring Size Guide".
General sizing advices
Our hands / fingers size fluctuate depending on the time of day, temperature and body chemistry. So it’s a good idea to size your fingers a few times over a day to find the most comfortable fit.
If you are opting for a broader style of ring, you may need to go slightly up in size.
Your ring should fit comfortably - loose enough that you can twist it off over your knuckle (with a little resistance) and not just slide off, and not so snug that it feels tight or uncomfortable.
If you have large knuckles/joints compared to the rest of your finger, your ring may feel a little loose when it’s on as it needs to be big enough to slide over your knuckle.
If you are buying a ring as a surprise gift, you can take an existing ring of theirs worn on the correct finger to a local jeweller to be sized.
In order to determine your bracelet size please follow the instructions given on the following link "Bracelet Size Guide".