A customer brings in an engraved 6 mm wedding band to size up 1.5 sizes. The shop stretches it on a roller, hands it back, and three weeks later the engraving has cracked and the band is visibly thinner at the front. Stretching is a fast, cheap resize, and it is the wrong call on any band wider than 4 mm, any engraved band, or any stone-set band. The choice between stretching and cutting-and-closing is decided by three numbers: target size change, current shank thickness, and what is on the band.
What stretching actually does to the shank
Roller stretching pulls the band outward on a mandrel, which thins the shank. A typical 2 mm shank stretched up two sizes drops to 1.5 to 1.7 mm at the front. That is below the 1.8 mm comfort minimum for daily-wear rings, and it is the failure point six months later when the band goes out of round. The karat reference on Wikipedia notes that softer alloys (14K yellow, 925 silver) stretch more easily but also thin more than hard alloys (18K, platinum), which is why the same stretch on 14K and 18K gives different wall loss.
Max stretch per band type
We stretch up to one size on plain 2 mm comfort-fit bands with no engraving, no stones, and a current shank thickness of 2 mm or more. Anything beyond that is a cut-and-close. Our earlier write-up on which bands can be resized covers the list; this article is about the decision math. On engraved or patterned bands, stretching smears the pattern across the stretched arc, which is what cracked the engraving in the example above.
When cut-and-close beats rolling
Cut-and-close means slicing the shank at the back, adding or removing a small wedge of matching alloy, and laser-welding the seam. It adds 10 to 15 minutes of bench time and $4 to $8 in labor, but it keeps the shank thickness at design. We choose cut-and-close on any band wider than 4 mm, any engraved or textured band, any stone-set band (especially pave, where stretching distorts the setting), and any resize larger than 1.5 sizes. Our note on shank repair weld versus remake covers the laser side; the link to when to resize and when not to explains that some rings should be remade, not resized at all.
Bench numbers we hold
Stretch max: +1.0 size on plain 2 mm comfort bands. Shank minimum after stretch: 1.8 mm. Cut-and-close wedge: matching alloy, laser weld, then polish to 600 grit. Weight check: we log original and post-resize weight on the QC ticket; a weight loss above 8% means the stretch went too far. The connection to finished ring weight tolerance is that a heavily stretched ring comes in 10 to 15% under spec, which the buyer notices on a scale.
Downsizing: cutting vs compressing
Sizing down is the mirror problem. Roller compression thins the shank the same way stretching does, so on any band wider than 4 mm we cut out a 1 to 2 mm wedge and close the seam rather than rolling the band smaller. The cut-and-close seam sits at the back of the shank, where it is invisible when the ring is worn, and the laser weld leaves a color match that polishing blends in. On engraved bands we also refuse to size down more than 1.5 sizes, because the engraving on the stretched arc compresses and crowds together. We send a photo of the marked cut line to the customer before we weld, so they know exactly where the seam lands on the inside of the band. We also re-measure the wall after the resize and log it on the ticket, so a future repair bench knows exactly what thickness it is working with and can plan the next weld accordingly.
FAQ: Ring sizing stretching vs cutting
How many sizes can I stretch up?
One size, maximum, on plain comfort-fit bands. Above that, cut and close. Stretching two sizes thins the shank below wearable minimum.
Does stretching weaken the ring?
Yes. Work-hardened silver and gold become springy and brittle after a stretch. If the band already feels stiff, cut and close instead.
Can I stretch a stone-set ring?
No. Stretching distorts the setting and loosens stones. Cut and close at the back of the shank, away from the head.
Why does my cut-and-close seam show?
Because the weld color did not match. Use a matching-alloy wedge, laser weld, and polish through 600 grit before the final high-shine pass.
Send us your resizing queue for a stretch-versus-cut decision per piece. We log shank thickness before and after, use matching-alloy wedges on cut-and-close jobs, and return a weight slip with every resize. Small-batch OEM custom manufacturing starts at 30 pieces per design; send the bands and we will quote the resize per piece.
Frequently Asked Questions
What ring sizes can you supply in bulk?
US sizes 5–12 including half sizes. Send a size breakdown with your order and we cast to that curve; comfort-fit inner bands reduce resize requests.
Can I order a mixed size run instead of one size?
Yes. Mixed runs are standard for wholesale: specify quantity per size and we pack and label by size at no extra labor cost.
What is the MOQ for custom ring designs?
50 pieces per design for existing molds; 100–300 pieces when a new mold or CAD model is required.
How should I price rings for retail margin?
Most partners use a 3–4x markup on FOB cost for sterling and 2.5–3x for moissanite solos, which keeps landed cost under 30% of retail.
