The new 12-sided £1 coin is set to enter circulation on March 28.
The old 'round pound' - introduced more than 30 years ago - will cease to be legal tender on October 15 as the new £1 is dubbed the most secure in the world.
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The new coins feature a string of security features including a hologram.
The hologram changes from a '£' symbol to the number '1' when the coin is seen from different angles
The Manchester Evening News reports around £1.3 billion worth of coins are stored in savings jars across the country, and the current £1 coin accounts for nearly a third of these.
People are being urged to return the £1 coins before they lose their legal tender status. They can either spend them before October 15 or bank them.
Some of the round £1 coins returned by the public will be melted down and reused to make the new £1 coin, which was announced in the 2014 Budget.
Replacing £1 notes, £1 coins were first launched on April 21, 1983. The Royal Mint has produced more than 2.2 billion round pound coins since that time.
But there have been concerns about round pounds being vulnerable to sophisticated counterfeiters. Around one in every 30 £1 coins in people's change in recent years has been fake.
When the new coin enters circulation on March 28, it might take a little while for people to start seeing it in their change as it gradually filters into general use.
The new coin is made of two metals, with a gold-coloured outer ring and a silver-coloured inner ring. It has an image that changes from a "£" symbol to the number "1" when the coin is seen from different angles. It also has very small lettering on both sides of the coin and milled edges.
It is thinner and lighter than the round pound, but its diameter is slightly larger.
Announcing the date when the new coin will enter circulation, Chief Secretary to the Treasury David Gauke said: "March 28 should be an important date in everybody's calendar this year - as we will have a new quid on the block.
"This is a historic moment as it's the first time we've introduced a new £1 coin since 1983, and this one will be harder to counterfeit than ever before.
"Our message is clear: if you have a round one pound coin sitting at home or in your wallet, you need to spend it or return it to your bank before October 15."
£1 coin factfile
Here are some facts about the new £1 coin and coins generally produced by the Royal Mint:
- The Royal Mint has produced over 2.2 billion round pound coins since 1983 - equating to the weight of nearly 6,000 elephants
- Twenty five different designs have appeared on the pound coin, from dragons to trees
- The Royal Mint will make over 1.5 billion of the new £1 coins
If you put these coins side by side, there would be enough to go from the UK to New Zealand and back
- The new £1 coin is based on the design of the old 12-sided threepenny bit, which went out of circulation in 1971
- It is being made at the Royal Mint in Llantrisant, Wales, at a rate of up to 2,000 each minute
- Some of the round £1 coins returned by the public will be melted down and reused to make the new £1 coin
- The oldest British coins in the Royal Mint's collection date back over 2,000 years.
Why the new £1 coin will be harder to counterfeit
- 12-sided – its distinctive shape makes it instantly recognisable, even by touch.
- Hidden high security feature – a high security feature is built into the coin to protect it from counterfeiting in the future.
- Latent image – it has an image like a hologram that changes from a '£' symbol to the number '1' when the coin is seen from different angles.
- Micro-lettering – it has very small lettering on the lower inside rim on both sides of the coin. One pound on the obverse "heads" side and the year of production on the reverse "tails" side, for example 2016 or 2017.
- Bimetallic – it is made of two metals. The outer ring is gold coloured (nickel-brass) and the inner ring is silver coloured (nickel-plated alloy).
- Milled edges – it has grooves on alternate sides.