Jewellery Making Math: Ring Sizes, Metal Weights, Alloy Purity, Bead Counts & Pricing Pieces

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Turn measured finger circumferences into inner diameters with PI, find the next larger size number and size letter with an approximate XLOOKUP, and show how much room each ring leaves.
• Calculate the strip length for a ring from its inner diameter and thickness, add a filing allowance to the width, and work out how much wire a batch of jump rings needs including the saw cuts.
• Look up wire diameters from a gauge table and calculate the weight of wire and sheet pieces from their volume and the density of the metal, so you can order and price metal by the gram.
• Convert karat to fineness, calculate how much fine gold a piece contains and use a mass balance to find how many grams of two metals give a batch of a target fineness.
• Value each piece by its fine metal content and a fictional price per gram, work out what a refiner would pay for it as scrap, and build a sensitivity table with mixed references.
• Count how many beads fit on each strand with INT, turn multi-strand designs into packs to buy with ROUNDUP, and split a beading length into full pattern repeats and a leftover with INT and MOD.
• Count how many stones fit around a full, half or partly set band with INT, cost them, total a findings bill of materials with SUMPRODUCT and budget a batch with a loss allowance.
• Price a small collection from materials, silver and making time plus overhead, set rounded retail prices from wholesale and retail factors, add a metal surcharge when the silver price rises and chart the collection.