How the 2012 Olympic medals are made

LLANTRISANT, WALES (CNN) - The medals for this year's London Olympics are locked away at the tower of London, ready for the games to begin.

The newly-minted gold, silver and bronze discs will be entrusted to the Beefeaters, custodians of the crown jewels.

The Royal Mint may be owned by the British government, but that was no guarantee it would win the contract to make the 4,700 medals to be presented at the London Olympic and Paralympic Games.

The mint says it beat out more than two dozen other contenders to make sure the medals have a real British connection.

"This wasn't about making money, this was about us having the right to do it," said Adam Lawrence, CEO at The Royal Mint. "Now, we are a broader licensee of the games too. So, we make quite a decent range of commemorative coins and products for the Olympic Games. And that's where we will make money on it."

So no profit from these medals, but the pride here is palatable among the workers.

"It was really nice [to win the contract], for the Royal Mint, but also for the people around who will get jobs doing this, as well," said Sian Merry, a seamstress at The Royal Mint.

The Royal Mint said its engraver is likely the only person who will touch every single London medal.

"Nice, I didn't even realize until now. I was the only person to touch every medal. Quite nice," said engraver Marie Buckley.

Before the etching, the medals have to be formed and then dipped in sulfuric acid.

There is a vat for the bronze medals and another for the silver ones, but none for gold.

Because the medals aren't really gold; they're same as the silver ones with just six grams of gold mixed in.

To put any more in there would make it far too expensive. Later in the process it will be gold plated. But in truth it is a silver medal made to look like gold.

And a bronze medal is mostly copper and tin, which is mined by Rio Tinto in Utah and Mongolia.

"It's a hell of a series of milestones you've got to meet to get the materials here in time and then make the medals in time," said Andrew Harding with Rio Tinto. "You can't be late, because the athlete is not going to stand there and wait for you."

You might also have noticed that the London medals are big - very big. Compare these to the ones presented in Athens in 2004.

"We effectively went for the biggest medal that we could, that we could manufacture," said Gavin Elliot with The Royal Mint.

Once the medals are struck, they have the goddess Nike on one side and the River Thames and a bit of 2012 branding on the other.

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