A buyer sends a CAD render and writes in the order notes: "as drawn, no tolerance needed." The engineer opens the file and applies the factory's default tolerance sheet without saying a word. Six weeks later the first 100 rings arrive, and 7 percent of them are US 7.25 instead of US 7. The buyer complains. The factory points to the default tolerance the buyer never asked to change. Tolerance on a custom jewelry job is not invented per order — it is a standing sheet, and you should know what it says before you quote your own customers.

Ring size and inner diameter

Our default ring size tolerance is plus/minus 0.15 mm on the inner diameter, which is roughly one quarter of a US half-size. That is tight enough for most retail bands and loose enough that we can hold it on 500-piece runs without rework. On heavy 14k bands we widen to plus/minus 0.20 mm because gold springback after polishing is higher. The fineness and marking obligations that apply to the finished ring are set out in 16 CFR Part 23 in the eCFR. The overall CAD spec a factory expects from a client is detailed in what a factory needs from your CAD file.

Wall thickness and weight

Structural walls on silver rings are held at plus/minus 0.1 mm off the CAD nominal. On thin earrings (0.5 mm wall) we widen to plus/minus 0.15 mm because investment burnout warps delicate waxes. Weight tolerance is plus/minus 5 percent on silver and plus/minus 3 percent on gold. If a buyer needs tighter (for a branded product sold by exact gram), we will hold plus/minus 2 percent on gold but the per-piece price rises because we have to hand-file mass instead of barrel finishing. The resolution of the wax print itself sets a floor on this, because a rough print leaves layers that polishing cannot fully remove on delicate walls.

Stone seats and metal finish

Stone seats are cut to the measured girdle of the actual stone lot, plus a default minus 0.05 mm (the seat is slightly smaller than the girdle so the stone compresses in). If a buyer does not supply girdle data, we default to the nominal size minus 0.03 mm — which is why sending the girdle report matters. Finish default is high polish at Ra under 0.15 micrometers; brushed is Ra 0.4–0.6. The girdle geometry we cut to is explained in moissanite girdle and seat cut fitting. The CAD-to-production timeline these tolerances feed into is in custom ring CAD to production timeline.

When to override the defaults

Three situations push us off default. First, a retail brand selling by exact ring size in half sizes needs plus/minus 0.10 mm. Second, a design with invisible-set stones needs the channel cut to plus/minus 0.02 mm because the stones slide in by compression. Third, a hollow piece that must stack identically with another part needs matched diameter on both halves. We flag these in the quote. A wax prototype approval step before production is our safety net — see custom ring wax prototype before production.

How tolerances shift on repeat orders

On a first order we hold the defaults and measure every piece. On the second and third reorder of the same SKU, we tighten automatically: ring size narrows to plus/minus 0.10 mm because the wax printer is dialed in, and weight narrows to plus/minus 4 percent on silver because we have a finished-piece reference to file against. What does not tighten is the stone seat. That stays tied to the actual girdle of the new stone lot, because every shipment of moissanite or CZ shifts slightly from the supplier. We send a one-page variance report with every reorder so the buyer can see the numbers move tighter as the run matures, and we never loosen a tolerance without telling the buyer first.

What if I need tighter than your default?

We can hold most tolerances tighter, but expect 10–20 percent more unit cost and a longer lead time. Tighter is a choice, not a free upgrade.

Do defaults change between silver and gold?

Weight tolerance and wall thickness widen slightly for gold because of springback. Ring size tolerance stays the same.

Can I see the tolerance sheet before ordering?

Yes — we send a one-page tolerance PDF with every quote. Ask for it specifically; it is not on the standard price list.

What is the tolerance on laser engraving depth?

Plus/minus 0.02 mm depth, plus/minus 0.05 mm position. On batch engraving we hold the position tighter by running a test piece on the first ring of the shift.

Send your CAD and we will return the default tolerance sheet with your quote. HOLYCOME runs CAD review, wax printing, and casting under one roof — ask about our custom manufacturing program and upload your .3dm or .STEP for a same-day feasibility and tolerance review.

Frequently Asked Questions

How do I verify a factory before placing a bulk order?

Request a production video, business license, export records and a paid sample run. A factory that accepts a 50-piece test order is usually a real manufacturer.

What payment terms do you offer?

30% T/T deposit with the balance against the bill of lading. This protects both sides on first orders and can move to net terms after a track record.

What is your normal reject rate?

3–5% under 10x loupe inspection for cast and set pieces. Defective units are replaced free in the next shipment.

Where is the factory located?

Wuzhou, Guangxi, China—the core lab-grown and moissanite manufacturing cluster. Shipments go via Guangzhou or Shenzhen ports.