Metal density in jewelry: why the alloy matters
Metal density is how much a given volume of metal weighs, in grams per cubic centimetre (g/cm³). Multiply a ring's metal volume by the density of its alloy and you have the ring's weight. The alloying metal matters as much as the karat: at 14K, white gold is 12.61 with nickel and 14.11 with palladium.
3D Jewelry Designer1 min read
From volume to weight
CAD software usually gives volume in cubic millimetres, so divide by 1000, then multiply by the density. A band with 210 cubic millimetres of metal weighs 2.74 grams in 14K yellow gold and 3.27 grams in 18K. That is the weight as drawn, before casting loss. The metal weight calculator measures the volume from the file for you.
Why the alloying metal matters
Karat sets how much of the alloy is gold, but the other metals change the density too. The same band weighs 2.65 grams in 14K white gold with nickel and 2.96 grams with palladium. Platinum 950 runs from 20.1 g/cm³ with cobalt to 21.5 with iridium. Use the figure for the alloy your caster pours: the alloy density table lists the common ones, each with its supplier source.
Density in the app
In the Playground, Measure weight lists the weight in every metal that has a density set up. Unconfirmed marks a supplier figure nobody has approved yet, and a metal with no density shows no weight. With cost-based pricing on, the ring builder prices each ring's metal from its measured grams.
Questions
Is specific gravity the same as density?
For weighing jewellery, yes. Specific gravity is density relative to water, which is very nearly 1 gram per cubic centimetre, so a specific gravity of 15.58 means 15.58 grams per cubic centimetre.
Related
- Jewelry alloy density table: gold, platinum, silver
Density of every common jewellery casting alloy in grams per cubic centimetre, with the supplier table each figure comes from.
- 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.
- Gold karat: what 10K, 14K, 18K and 24K mean
Karat measures gold purity in 24ths. The fineness of 9K to 24K gold, and how karat changes a ring's colour, weight and gold price.