Gold comes in through the front door of Baird & Co in the East End of London in many forms. This bag of broken and unwanted jewellery had just arrived, when BBC Radio 4's Money Box team visited. (Photos and words by Money Box presenter, Paul Lewis)
This 12.5kg standard gold bar from Kazakhstan is the size of a house brick, but rather thinner - and with a value of �250,000, it is worth more than the average house.
Scrap jewellery or gold bars - whatever form the precious metals come in, they are melted down in these crucibles. The liquid metal - what they call "the melt" - is tested and the owner is then paid for the precious metal content.
The liquid metal cools quickly in the iron mould, and the crucible - or pot - cools too. Each customer has their own pot, so any scraps left behind are there next time.
When it has cooled, the bar is sent off to have the precious metals extracted. Gold, silver, palladium and platinum are kept. Other metals are dumped.
Staff on the engineering factory floor turn the precious metals into investment ingots, wire, electronic components, coins - and even wedding rings.
The smallest gold investment bars on this tray weigh 2.5g, and have a value of �60. The bar held in factory-owner Tony Baird's hand weighs 1,000g and would sell for around �20,000.
Although it looks like any factory from the outside, security is tight - no-one gets in or out without permission. You can find out more about what goes on inside the factory gates on BBC Radio 4's Money Box on Saturday at 1204 BST.
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