Like many other mints, the Royal Mint issues bullion coins in precious metals, having much higher intrinsic value than their face value. Most of these by tradition are measured in troy ounces of fractions thereof, but the mint also introduced metric coins measuring one kilogram of pure metal (they are actually fractionally heavier as a whole, to account for the small amount of other metal in the alloy).
The 1 kg gold coins are denominated as One Thousand Pounds (£1,000), although their intrinsic (bullion) value is much higher than their face value. The coins vary in design depending on the occasion (they are "one-year" types usually issued in parallel with smaller denominations with the same reverse designs).
The coins are legal tender but are not intended for circulation. They are targeted at bullion investors or collectors who appreciate the special editions as pieces of art.
The 2018 Year of the Dog bullion coins are part of the Royal Mint's Shēngxiào Collection - a coin series dedicated to the Chinese Lunar calendar.
As the mint says:
"For centuries The Royal Mint has drawn upon its unrivalled heritage, experience, and craftsmanship to evolve and meet the needs of an ever-changing market. In 2014 we struck the United Kingdom’s first Chinese Lunar coins, introducing a new series and a United Kingdom first. The Shēngxiào Collection, named to honour the Chinese zodiac, is a celebration of the UK’s diverse multi-cultural society. At Chinese New Year, gifts and tokens are exchanged, particularly the gift of money in red envelopes, symbolising good wishes for the recipient’s health, wealth and prosperity. These Lunar coins from The Royal Mint embrace this globally observed tradition, lending a unique British angle to an ancient tradition."
"People born in the Year of the Dog are loyal and observant. They are trustworthy and can always keep a secret. Just as pet dogs are considered loyal companions, people born in the Year of the Dog are said to be true and dependable friends and they can’t do enough for the people they are closest to. While they can jump to conclusions, they are generally straightforward and friendly people.
Dogs are honest, friendly and compassionate, careful and practical, but as they are not very good at communicating, it is tough for them to express their thoughts to others. They have a good nature, meaning that they tend to do things by the book and follow the rules. They like a quiet life and a close family relationship makes them happy and content."
The 1kg gold coins were issued in a presentation box, in Proof FDC grade only (Royal Mint Product Code: UKD18GK). | 
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