Ring sizing can be a tricky business even for the professionals. It really is about finding the best fit for you. There is a lot of mixed messages and false information out there that I'm going to do my best to explain so that you can achieve the right outcome and be confident in your sizing.
As a general rule I tell all my clients you want to be able to push it on easily but then twist it off.
You will find at different times of the day your ring may be tight or lose as your body temperature fluctuates throughout the day. This means you are looking to get sized when you feel neither hot or cold to get your optimum fit.
The best thing to do is get sized from the jeweller you are getting your ring from. There are some variables on ring sizers. Next best is another jewellers - any high street shops will have ring sizing tools and usually do this free of charge. They will get you to try on metal sizers - these come in various widths and its best if you can try the width for the band you want. AKA If you know you want a thin ring - sizing from a 2mm ring sizer is best. If your looking for a thicker band sizing from a 4mm is better. You will likely be a slightly bigger size for the wider ring.
If you are getting the ring as a surprise... stealing a ring they wear is another option. If you know the ring fits well this is a safe bet. However..... I've had lots of people steal rings and they are perhaps not the best fit and so still need resized. Sometimes old worn rings are also mishapen and not a true circle so give a false reading. The other reason this doesn't always work is often your ring size is different on your dominant hand. So if your stealing a ring they wear on their right hand it can be a size bigger than their left hand if they are right handed. If your worried about stealing the ring away to get sized there is another option ... trace the inside of the band carefully on a piece of paper and measure the diameter then match to the chart below.
A last resort would be using string, plastic sizers, downloadable paper sizers etc ... these will not give you accurate results.... I would advise against this option. If you are going to go to these lengths and share this with your partner anyway, its far better to just make the time to go to your local jewellers and get sized.
It your knuckle is your widest point you will find you will have swing or movement at the base of your finger. Don't be tempted to go smaller, it is important you can take it off. I hear lots of girls joke to their partners they don't need to be able to take it off but for health reasons you should always be able to get it in on and off as you could cause yourself a serious knuckle injury and can cause arthritis in later life.
If you lose or gain weight your ring size is likely to change. If you are pregnant the fluid in your body is likely to increase also and will cause swelling in your fingers. It is probably best to wait till you feel at your "normal" weight before proceeding with ring sizing. Also advised to take any rings you do have off when pregnant if your suffering with swelling.
I offer a free resize with all my rings but the preferable option for both your and your ring is that it will not need resized and you can enjoy wearing it straight away.
It's worth considering that not all rings can be resized due to their style/ shape /condition. Full eternity set rings can not be resized and usually it is not advised not to size up or down by more than 2 or 3 sizes. Resizing will usually leave a visible solder line on white metals or rosegold. Resizing costs £50 plus postage.
Times you should avoid wearing your ring.
1. At the gym or while doing exercise - your hands are likely to swell with increased blood flow, increased temperature and become tight and cause discomfort. Contact sports can also cause injury. Metal contact with machines and equipment may damage your ring.
2. In the shower/swimming and when washing up/cleaning - soaps and grease residue will build up with ongoing exposure and moisture trapping between skin and metal can cause "ring rash". Chlorine and harsh cleaning products can also damage your jewellery or stones.