Melt value starts with fine metal weight

Coins, bars and jewellery can have a gross weight that includes metals other than gold or silver. Purity converts that gross amount into fine metal. A 10 gram 18-carat gold item at 75% purity contains an estimated 7.5 grams of fine gold. The remainder is alloy, solder or other material and is not valued at the gold spot price.

1. Standardise weight
   Convert the selected unit and item quantity into total grams.
2. Apply purity
   Multiply gross grams by the entered percentage.
3. Convert to troy ounces
   Divide fine grams by 31.1034768.
4. Apply the AUD quote
   Multiply fine troy ounces by the supplied metal price.

With the default entries, one troy ounce of 99.99% gold contains 0.9999 fine troy ounces. At the deliberately round $5,000 reference price, theoretical melt value is $4,999.50. A dealer bid 2% below melt is $4,899.51, while a retail scenario 5% above melt is $5,249.48. Replace every market assumption before using the result.

Troy ounces and ordinary ounces are not interchangeable

A precious-metal troy ounce is 31.1034768 grams. An ordinary avoirdupois ounce used for many everyday goods is about 28.3495 grams. Entering a one-ounce kitchen-scale reading as one troy ounce overstates weight by roughly 9.7%. The unit selector keeps the distinction visible and reports the converted gram total.

Purity marks need verification

Fineness states pure metal parts per thousand or as a percentage. Gold marked 9999 is 99.99%; 999 is 99.9%. Traditional gold carat indicates parts of gold out of 24, so 24-carat is nominally pure, 22-carat is about 91.67%, 18-carat is 75%, 14-carat is about 58.33% and 9-carat is 37.5%. Sterling silver is commonly 92.5% silver.

A stamp is evidence to investigate, not a laboratory assay. Counterfeit marks, wear, repairs, mixed-metal chains, hollow parts and filled items can make a simple weight-and-purity estimate inaccurate. Electronic testing, X-ray fluorescence or fire assay may be appropriate depending on value and the transaction.

Spot, bid and retail prices answer different questions

Spot price is a reference for metal traded at a particular place and time. Australian buyers need an AUD price or must convert a foreign-currency quote using a matching exchange rate and timestamp. Gold and silver prices can move while a dealer is preparing a quote, so a saved result without time and source is not reproducible.

Theoretical melt value assumes every gram of fine metal receives the reference spot price. A refiner or dealer may pay less to cover testing, refining, hedging, handling, minimum lot size and margin. The bid-discount field creates a transparent scenario; it is not a claim that all dealers use the same percentage.

Retail bullion often sells above melt because minting, distribution, security, demand and dealer costs create a premium. Small bars and coins commonly have a higher percentage premium than large wholesale units. Limited mintage and collectable demand can add numismatic value that has little relationship to metal content.

Why the page does not display a “live” gold price

A real-time claim requires a reliable licensed feed, currency convention, bid/ask definition and timestamp. This self-contained WordPress module has none. A hard-coded number would become stale and could mislead. The manual spot field makes the price assumption auditable and prevents the page from targeting the separate “live gold calculator” intent dishonestly.

Australian tax and transaction treatment are separate

GST treatment does not follow the word “gold” alone. Australian tax law has specific definitions for investment precious metal, including minimum fineness and trading characteristics. Jewellery, collectables, scrap and some coins can have different GST outcomes. The calculator reports a pre-tax metal value and does not add or remove GST.

Buying or selling bullion can also have income-tax or capital-gains consequences depending on purpose, ownership, business activity, acquisition records and whether a personal-use or collectable rule applies. A dealer’s cash offer is not the taxable gain. Keep purchase invoices, dates, quantities, serial numbers, fees and disposal records, and obtain tax advice for material transactions.

Insurance replacement value can exceed both melt and dealer bid because it may include fabrication, retail margin, matching items and appraisal costs. Conversely, an insurer may require a current professional valuation and security conditions. Use the result only for its labelled intrinsic-metal question.

Measure before multiplying

Use a calibrated scale appropriate to the lot size. Weigh identical items together when the scale performs better at a larger mass, then enter quantity one and the total weight, or enter a reliable per-item weight and quantity. Do not round purity, unit conversion or fine ounces prematurely; the page keeps precision internally and rounds only displayed amounts.

For a large lot, separate pieces by metal and purity. Averaging 9-carat and 18-carat jewellery into an assumed 13.5-carat mixture can hide incorrect weights and makes later verification harder. Run one worksheet per homogeneous group and add the quoted dealer values only after checking each assumption.

Create a like-for-like dealer comparison

Ask each buyer whether the quote is based on gross weight or verified fine weight, which price timestamp applies, whether the percentage is before or after assay and refining fees, and how payment will be made. A dealer advertising “up to spot” may apply that rate only to particular bullion products while offering a different schedule for scrap jewellery. Enter the final effective bid percentage, not an attention-grabbing headline.

For a mixed parcel, record each group separately and calculate a weighted total. Ten grams of 18-carat gold and ten grams of 9-carat gold contain 11.25 grams of fine gold together, not 20 grams at an average chosen by appearance. Keeping individual worksheets also exposes a buyer’s different deductions for low-purity material.

When comparing a purchase, use the same spot reference and time for every product. Calculate premium as the asking price above melt, then consider delivery, card surcharge, storage, insurance and eventual buy-back spread. A coin with a low advertised premium may cost more after delivery or receive a weaker bid. The retail scenario on this page applies one percentage only; add transaction costs outside the worksheet.

For repeated monitoring, do not overwrite the old price. Save a dated copy so changes can be separated into metal-price movement, currency movement, premium movement and quantity. That record is more useful than a screenshot showing only a final dollar value with no purity or source.