Bangko Sentral ng Piilipinas

Refined Gold and Silver

How gold and silver are refined

The refining of gold and silver consists of the following stages:

Evaluation melting. The raw bullion is melted in a crucible, and dip samples are taken to determine its content of gold, silver and other elements.

Chlorination. Gold is separated from other elements, mostly silver and base metals. When this is done, the gold and silver are then cast for the next stage

Melting/casting to bars. The refined gold and silver are separately melted and cast into bars.


“Good delivery bars”

“Good delivery bars” are the final output of the refining process. Good delivery gold bars weigh from 350 fine troy ounces (10.9 kg) to 430 troy ounces (13.4 kg) and have a minimum purity of 99.5%. Good delivery silver bars weigh approximately 1000 troy ounces (31.1 kg) and have a minimum purity of 99.9%.

The following are the London Bullion Market Association’s (LBMA) requirements for assaying and bar quality:

Weight: Approximately 400 fine troy ounces (approximately 12.5 kilograms)


Minimum acceptable fineness: 995.0 parts per thousand fine gold


Top Surface: 260 mm x 85 mm
Bottom Surface: 230 mm x 60 mm
Thickness : 37 mm

Bars that meet these specifications are acceptable in the London market.

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