Accurate Determination of Finger and Ring Sizes

Ring remains upright and does not turn freely

Ring does not come off easily

Sizing a ring requires an accurate measurement of the customer’s finger or ring

Finger-sizing gauges are also available with convex inner surfaces

Wide-finger sizing gauges are used to determine finger size for wide rings such as fashion rings and wide bands (over 4 mm in width)

The size of a customer’s ring is determined using a ring sizing stick or ring mandrel made of tapered wood, plastic, or aluminum that is marked in quarter, half, and full-size increments (These increments equate to inside diameter increases of approximately 0.2 mm, 0.4 mm and 0.8 mm respectively).

To do sizing work, bench jewelers use a steel ring mandrel made of tapered, milled steel; and marked in quarter, half, and whole sizes (0.2 mm, 0.4 mm and 0.8 mm, inside diameter respectively).

All finger-sizing gauges, ring sticks, and ring mandrels must be calibrated to one another so measured sizes are consistent throughout a retail store, a trade shop, or a manufacturing company

Calibration of tools is important for operations with multiple locations, such as a retail store that sends work to a trade shop, or manufacturing companies that do special orders or custom work for retailers

Sizing or handling a ring with an exposed culet is not advisable. This is considered a design flaw and a jeweler cannot safely and accurately size the ring without risk of damage. In this situation, consider an alteration, a change of setting, or a remount.

The correct size should be just loose enough to pass over the finger joint and settle at the position on the finger where the ring will be worn

Gently slide the finger-sizing gauge onto the customer’s finger. Never force it over the joint.

Every hand is unique. Judge each fitting on a case-by-case basis to determine what ring size is most comfortable for the customer.

Allow the customer to put the finger-sizing gauge on and take it off

Because fingers swell and contract, a finger size should be taken on three different occasions to confirm the measurement

Alternate between sizes in the event that the customer wants the finished ring to fit snugly or loosely

Record the size on the job envelope, along with any special instructions, such as requests to preserve special engraving

Be sure to indicate the finger for which the ring is being sized

For accuracy, be sure the new ring is the same shape or configuration as the sample ring. Determine if the ring being measured is round. If the shape is distorted, gently round it with a rawhide or nylon hammer on a steel-ring mandrel before determining size.

Slide the ring gently onto the ring stick until it is snug, but do not force it as the measurement could be inaccurate

This customer’s ring is a size 6.75 (17.1 mm inside diameter).

On the ring stick, read the ring size at the line on the stick where it touches the central point of the width. This example is a size 9.0 (19.0 mm inside diameter).

Determine the size at the line where the central point of the narrowest part of the ring touches the ring stick. The narrowest part of the ring might be the top or the bottom of the shank. This ring is size 5.25 (15.9 mm inside diameter).

Determine the size at the line where the central point of the narrowest part of the ring touches the ring stick. The narrowest part of the ring might be the top or the bottom of the shank. This ring is size 6.50 (16.9 mm inside diameter).

Wide rings have more metal that contacts the skin, and fit more tightly on the hand

On a ring stick, the size is determined at the line on the mandrel that touches the central point of the ring’s width. In this example, the band is a size 7 (17.3 mm inside diameter).

Wide rings might need to be one-half to one full size (approximately 0.4 mm to 0.8 mm US finger size inside diameter) larger than narrow rings, depending on the finger joint size and the customer’s comfort.

Even if a customer feels they know their ring size, always check it. This tapered ring is a size 6.75 (17.1 mm inside diameter).

To prevent loss or damage before the rings are joined together, the engagement ring might have to be adjusted while being worn alone

Measure the bride-to-be’s finger using a wide-finger sizing gauge. However, rings worn individually might be loose, especially when her hands are cold.

When the rings are soldered together, they can be resized as a unit. However, this means there is potential for an additional sizing joint on the engagement ring.

To fit a ring with a convex inside shank, use the narrow-finger sizing gauge

Determine the size at the point where the center of the ring or band touches the sizing stick. Then measure one-quarter size smaller.

Size the ring one-quarter size smaller than the measured finger size. For example, if the size 7 (17.3 mm inside diameter) gauge fits, size the ring to a 6.75 (17.1 mm inside diameter).

In these examples, the flat-top band is a size 5.5 (16.1 mm inside diameter) and the half-round band is a 6.75 (17.1 mm inside diameter).

To fit a ring with space between the top of the finger and the mounting, use the appropriate finger-sizing gauge (narrow for shanks less than 4 mm wide and wide for those greater than 4 mm wide). If the opening is 3 mm to 5 mm, subtract at least a quarter-size from the measured ring size.

Determine the size at the point where the center of the narrowest part of the ring touches the ring stick. Then adjust the size according to the width of the opening at the top of the shank. With the opening at the top, this ring will fit a size 5.75 (16.3 mm inside diameter), not a 5.5 (16.1 mm inside diameter).

Although sizing beads can be a potential solution for keeping a ring from turning on the finger, they do not always satisfy customers. They take up about a half- size of space and tend to be uncomfortable to wear.

Soldering two small beads onto the inside of a ring shank is the simplest way to keep a ring from turning when the finger is 1.5 (1.2 mm US finger size inside diameter) or more sizes larger than the area where the ring sits.

Installing a spring insert is an excellent way to keep a ring sitting straight on a finger. The spring, made of highly tensioned platinum, resembles a horseshoe and will hold the ring snugly. It is flexible and comfortable to wear, making it superior to sizing beads.

To maintain the tension or springiness of the insert, use a laser welder to install it. Using a torch will anneal the spring.