A ring should fit snugly enough to stay on your finger, but loosely enough to be taken off again without difficulty. The right fit lies somewhere in between: the ring slides on with a slight resistance and meets a clear, but not painful, stop at the knuckle when you try to pull it off.

Your finger is not the same size all day. It swells slightly in heat, after salty food and over the course of the afternoon, and becomes thinner in the cold and in the morning. A good ring should be able to accommodate these fluctuations without pinching or falling off.

What the right fit feels like

Try the ring on and push it past the knuckle. The resistance should be noticeable, but brief, so that you sense the ring will stay in place once it is on. If the ring sits on the middle joint of your finger, it should be able to turn around the finger without pinching, and the skin around it should not bulge up or be left with a deep mark.

The most important test is taking the ring off. A well-fitting ring requires a small, controlled tug over the knuckle, not a battle with soap and twisting. If you can pull it off completely without resistance, it is too big. If you have to twist, press and pull repeatedly, it is too small.

Test the fit at the end of the day, when your finger is at its thickest, and avoid measuring when your hands are cold.

Wide rings and signet rings feel tighter than thin rings in the same size, because more metal lies against the skin. If you have to choose between two sizes for a wide model such as an oval signet ring in sterling silver, the slightly larger one is often the more comfortable. A narrow ring band, on the other hand, can be worn more snugly without causing discomfort.

When the ring fits too loosely

A ring that is too loose turns on its own, so that the stone or the front faces towards the palm, and it can slide over the knuckle when you move your hand. This is especially a problem with rings where a centre stone needs to stay pointing upwards, such as on a solitaire ring or a round trilogy ring, where three stones need to sit level.

If a ring easily falls off, the risk of losing it is real. A jeweller can make a ring smaller by removing a small piece of the band and soldering it back together, and most rings with a smooth band can be adjusted a couple of sizes without problems. If the ring is set with stones all the way around, like an eternity ring, there is less room to work with, because the settings take up space on the band.

When the ring fits too tightly

A ring that is too tight leaves a red, deep mark in the skin that does not disappear quickly, and it can create a sensation of the finger throbbing or becoming cold further out. If the ring is stuck so that you cannot get it over the knuckle at all, it is too small and should not be worn daily in that state.

If a ring gets unexpectedly stuck, a little soap, hand cream or cold water can often help it over the knuckle. Hold your hand raised for a moment to reduce swelling, and gently twist the ring off instead of pulling straight. If the finger is already swollen, cold and rest usually do more good than pressing hard.

A tight ring can be enlarged by a jeweller. How much depends on the model: a simple band can be stretched or have a piece of metal inserted, while a ring with stones close together all the way around has narrower limits for how much it can be opened.

Find the right size from the start

The most reliable method is to measure a ring you already have that fits the finger the ring is to be worn on. Measure the inner diameter in millimetres across the middle, and find the size based on the measurement.

If you measure directly on the finger with a strip of paper or a piece of string, note that the string must also be able to pass over the knuckle. If the knuckle is clearly wider than the finger itself, you should choose a size that fits the knuckle, and possibly make the band a little tighter further in, so the ring does not turn.

How the fit lasts over time

The circumference of your fingers changes throughout life with weight, temperature and age, so a ring that fitted perfectly years ago may therefore pinch or fit loosely later. A narrow band follows the finger most closely, while a wide model is less forgiving when the finger changes circumference.

If several rings are worn on the same finger, they affect each other's fit, because they press against one another. A thin model such as a half eternity ring can be stacked closely, while a round pavé ring with stones on the surface takes up more space and preferably needs a little room next to the neighbouring ring. If a ring no longer fits, an adjustment at a jeweller is usually a simple solution that preserves the design.