The new 12-sided £1 coin, which comes into circulation on Tuesday, has been described by the Royal Mint as “the most secure” in the world.

The new coin will replace the existing round pound, of which about one in 30 are thought to be fake.

The round pound will remain legal tender alongside the new coin for just over six months until 15 October this year, after which retailers are under no obligation to accept it.

The high-security features include its distinctive shape and bi-metallic structure.

It also has an image that works like a hologram and micro-sized lettering inside both rims.

Around 1.5 billion of the new coins will be struck.

Here are all the subtle design features that make it safer:

1. Uneven sides

The 12-sides of the coin are uneven and make its distinctive shape instantly recognisable, even by touch, making forgery tougher.

2. Secret messages

The Government has employed a security technology company called Integrated Secure Identification System (iSIS) to fit the new coins with a special plating that can contain electromagnetic signatures.

It's also said to be especially hard to remove.

3. It's made of two metals

Like the £2 coin before it, the new pound will be made of two metals: nickel-brass on the outside and nickel plated solid alloy on the inside.

This, plus the 12-sides, is believed to make the coin safer than ever.

4. A bigger coin

The new £1 will be just under a millimetre wider than the current one, at 23.43mm compared to 22.5mm.

5. Grooves in the sides

The new £1 will have grooves in the sides, known as milled edges.

The 2016 banknote beauty pageant Show all 6 1 /6 The 2016 banknote beauty pageant The 2016 banknote beauty pageant currency of Scotland The 2016 banknote beauty pageant currency of Australia The 2016 banknote beauty pageant currency of New Zealand The 2016 banknote beauty pageant currency of Georgia The 2016 banknote beauty pageant currency of Belarus The 2016 banknote beauty pageant currency of Maldives

6. Secret images

Not only can the plating contain secret messages, but the design of the coin itself contains secret images, known as latent images.

It refers to pictures etched into the metal that you can only see when the coin is tipped to the light.

Like a hologram the imagechanges from a "£" symbol to the number "1" when seen from different angles.

7. A 'hidden' security feature

A high security feature is built into the coin to protect it from counterfeiting in the future.