Metal weight calculator: weigh a ring from its 3D file
Drop a 3D file of the piece and the calculator measures the volume of its metal, then weighs it in every common alloy from supplier densities. Stones modelled as separate objects are kept out of the metal weight and counted on their own, with their carats totalled. A .3dm keeps the units it was drawn in, and the file never leaves your browser.
3D Jewelry Designer1 min read
Weigh your model
How the weight is worked out
The calculator merges all the metal in the file into one solid, measures its volume, and multiplies by the density of each alloy. That is the whole calculation; how to calculate gold weight from a 3D model walks through it by hand with a worked example.
What makes the number trustworthy is everything before that multiplication. Overlapping metal parts are merged, so the metal they share is counted once. Stones are recognised and kept out of the metal. And anything that cannot be measured honestly is left blank with a note saying why, rather than estimated.
What it reads in each format
A .3dm file records the units it was drawn in, so a ring drawn in millimetres, centimetres or inches is weighed at its true size, and hidden objects and layers are left out. STL and OBJ files carry no units at all, and GLB exporters do not agree on them, so for those three the calculator infers millimetres from the finger hole and the stones, and lets you correct it.
What the number is not
It is the weight of the model, not of a finished casting. Sprues, casting loss and polishing change what you pour and what you sell, and a caster carries their own allowance for those. It is also the weight at the size the file was drawn, so a ring modelled at one finger size weighs what that size weighs.
Questions
Is the weight net or gross of the stones?
The headline figure is net: stones that are separate objects in the file are left out of the metal and counted on their own. The gross figure underneath adds them back at 0.2 g per carat, which is the definition of a carat rather than an estimate.
Why is the weight far too high or too low?
Almost always the units. STL and OBJ files do not record them and GLB exporters disagree on them, and weight grows with the cube of size, so a model read at the wrong scale is badly off. The calculator first infers millimetres from the finger hole and the stones; if it cannot, it leaves the weight blank. Pick the units the model was drawn in and it measures again.
Which white gold does it weigh in?
Both. Nickel white gold and palladium white gold have different densities at the same karat, so each is listed separately, with the supplier table its density comes from.
Does the weight include casting loss?
No. It is the weight of the model as drawn, with no allowance for sprues, casting loss or polishing, at the size the file was modelled at.
Related
- How to calculate gold weight from a 3D model
Work out the metal weight of a ring from its CAD volume and the alloy density, with the published density figures for 14K, 18K, white gold and platinum.
- Casting loss in jewellery manufacturing
Casting loss is the metal that never reaches the finished piece: sprues, flashing and polishing. It is why a cast ring weighs less than the metal poured.
- 3DM viewer: open a Rhino file online
Open a Rhino .3dm file in your browser, rendered as jewellery, with every part, its layer and whether it is metal or stone listed. No Rhino needed.