Engagement Rings
How Close Is Close Enough?
Every number in a ring specification has a tolerance around it β and knowing which ones are tight tells you what to check on arrival.
Written by the Mapple Gems workshop, Surat Β· Updated 10 October 2026
Short answer
Some numbers are near-exact and some genuinely vary. Stone millimetres and ring size are tight β a tenth of a millimetre matters, because seats are cut to a specific girdle. Gram weight varies more, since casting and finishing remove metal unevenly; a few percent either way is normal. Shank thickness should be held closely, because it is structural. When something arrives noticeably different from the written specification, the useful question is which number moved and by how much, not whether variation exists at all.
Handmade objects are not machined parts, and a certain amount of variation is inherent. But not every number varies equally, and confusing the two leads people to accept things they should question β and to question things that are entirely normal.
The reason stone measurements are held so tightly and gram weight is not comes down to one thing: the stone is measured before the ring exists, and the metal is removed after. A setter cuts a seat into each prong β a notch the girdle sits inside β and those seats are cut to the actual stone in front of them. A tenth of a millimetre out and the stone sits high, tilts, or grips unevenly. That is why a head cannot be built from a carat figure, and why we ask for measurements rather than weight when setting a stone we did not supply. Gram weight behaves completely differently. A casting comes out rough and oversized, and then metal is removed: filed at the sprue, cleaned in the gallery, softened at the interior edges, polished at every surface. How much comes off depends on how the casting came out, so two identical rings from one mould can finish a few percent apart in weight without anything being wrong. So a gram weight a little under the quote is ordinary; a centre stone a full half-millimetre under is not. One is the process, the other is a different stone.
Which numbers hold, and which move
| Specification | How tight | Why |
|---|---|---|
| Centre stone mm | Very tight | Seats are cut to this stone |
| Ring size | Very tight | A quarter size is felt |
| Shank thickness | Tight β it is structural | Decides twenty-year life |
| Band width | Fairly tight | Visible against a band |
| Gram weight | Looser | Metal removed in finishing |
| Melee size | A stated range | Bought as a parcel |
| Profile height | Fixed at casting | Not adjustable afterwards |
Melee is a range, and always was
Worth understanding because it looks like imprecision and is not. Accent stones under about 0.20Β ct are never individually certified in any material β they are bought as a parcel with a stated size range, colour range and clarity range.
So a specification saying β1.2β1.3Β mm, GβH, VSβSIβ is not vagueness; it is how the material is sold. What you should expect from good work is consistency within that parcel, which is visible: look straight down the row in daylight and every table should sit level, with even spacing and no gaps of exposed metal.
Keep the parcel specification. It is the only reference that exists if a stone is ever lost and needs matching.
Where the stone itself varies
Two figures on a grading report are worth reading against the standard rather than in isolation.
Measurements against expected size. A round sold as one carat should be about 6.5Β mm. A stone measuring larger than standard for its weight has been cut shallow to spread β more face, less light returned. That is a genuine warning rather than a bonus, and it is entirely visible on the measurements line.
Carat weight itself. Reports state weight to two decimal places, and stones are cut to land just above a round number because prices step there. That is also why just-under weights are good value: 0.90Β ct measures 6.2Β mm against 6.5 at a full carat β three tenths of a millimetre nobody detects, at a price set below a threshold.
On arrival: what to measure and what to accept
- Check against the written specification, not the listing photographs. That is what the piece was made to.
- The metal stamp inside the shank, and the girdle inscription against the report number.
- Ring size, worn at the end of a normal day. Fingers are largest then, and a ring that fits in the morning may not at six oβclock.
- Stone row level in daylight, and press each stone with a fingernail.
- Report anything wrong the same day. Windows are short and weaken with every day that passes.
And one thing that is not a fault: a real ring correctly looks smaller and calmer than macro product photography, which is shot at close range under directional light. That is the camera, not a discrepancy.
How to raise it if a number is off
Be specific rather than general. βThe shank measures 1.5Β mm at the base and the specification said 1.8β is a conversation with one answer. βIt feels thinner than I expectedβ is not.
A workshop that gave you numbers up front can check its own records against the piece, which is another reason to ask for the written specification before ordering rather than after. Where it turns out the variation is genuine process β a gram weight slightly under β a good seller will explain why rather than dismiss the question, and that explanation should match what is on this page.
Keep reading
Frequently asked questions
Why is my ringβs gram weight different from the quote?
Because metal is removed after casting β filing, cleaning the gallery, softening interior edges and polishing all take material off, and how much depends on how the casting came out. A few percent either way is ordinary; a large difference is worth asking about.
How exact should stone measurements be?
Very β a tenth of a millimetre matters, because seats are cut into each prong to fit that specific girdle. A stone significantly different from the specification is a different stone, not a tolerance. This is also why a head cannot be built from a carat figure.
Why is accent stone size given as a range?
Because melee under about 0.20Β ct is never individually certified and is bought as a parcel with stated size, colour and clarity ranges. That is how the material is sold. What good work shows is consistency within the parcel β a level row with even spacing.
My stone measures larger than standard β is that good?
No β it means the stone was cut shallow to spread its weight across a wider face, which returns less light and often shows as a flat centre. A round sold as one carat should measure about 6.5Β mm, and the measurements line shows it.
Ask for the numbers before, so you can check them after.
A specification you hold turns βthis feels wrongβ into a question with an answer.
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