Start with net weight
Subtract non-metal weight from gross weight before valuing the metal. Ask whether a quoted rate already corresponds to the selected purity. Applying a 22/24 factor to an already-22K rate would incorrectly reduce the metal value a second time.
Identify the charge basis
Making charges may be a percentage, an amount per gram, a fixed amount or a stated combination. Our purchase tool adds the methods you enter. The comparison tool treats them as alternatives. Enter a wastage charge only if it appears on your quotation; do not invent one to match a bill.
Tax and discounts are explicit assumptions
Our manual tool subtracts the entered discount before applying the user-entered tax percentage to the subtotal. Actual tax treatment depends on the transaction. This is a declared arithmetic model, not a universal GST rule. Stone services or other charges may need separate treatment. An invoice difference is a prompt to ask questions, not proof of wrongdoing.