Accurate Determination of Finger and Ring Sizes

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.

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

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

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.

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).

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).

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.