Pricing gold jewellery from the live rate: purity, making and rounding
How an ounce price becomes a per-gram line total, and why the order of rounding changes the invoice by a few dollars.
Wholesale gold jewellery is priced from the spot rate at the moment of issue. The arithmetic is short but every step has a convention, and two exporters who round differently will disagree by a few dollars on the same parcel.
The four steps
- Ounce to gram. Divide the USD per troy ounce rate by 31.1035.
- Apply purity. Multiply by the karat fraction: 0.916 for 22K, 0.875 for 21K, 0.750 for 18K.
- Add the making charge per gram, agreed per product line.
- Multiply by net weight and round the line to two decimals.
Round the line, not the rate
AurumIQ keeps the per-gram price at full precision and rounds only the line total, then sums lines before applying rebate, freight, insurance and VAT. That order is fixed so the desktop app, the cloud workstation and the verification portal always recompute the same total from the same inputs.
Lock the rate on the invoice
The rate used is printed on the invoice and signed into the QR payload. If the market moves after issue, the document still verifies against the rate it was issued at.