The useful answer is narrower than a headline spot price. At Farringdon Precious Metals the confirmed offer is the payable weight of your metal multiplied by the buying rate for the purity we verify at 55 Hatton Garden. A website calculator can only estimate that.
Three figures that are easy to mix up
The spot reference is the live market price of fine gold, usually discussed per troy ounce and converted to grams. It is not a payout.
The buying rate is our purchase price for a stated purity, such as 9ct or 22ct, after the margin we work to. That rate is already adjusted for fineness. We do not multiply by purity again.
The estimated offer is payable grams times that buying rate. The confirmed valuation replaces the estimate once the item has been weighed and tested in front of you and you accept.