Half sovereign - British coin - was created in 1544.
No. The British gold Guinea coin was a coin with a value of 21 Shillings and was 24mm in diameter. The Guinea was last issued in 1813 and was effectively replaced by the Sovereign. The British 22 carat gold Sovereign coin is a coin with a face value of One Pound (or 20 Shillings) and is 22.05mm in diameter. The modern Sovereign was first issued in 1817.
A Sovereign is Sterling coin. In 1880 a Sovereign was worth a Sovereign or One Pound. It's face value has not changed since it was reintroduced into the currency in 1817.
Your coin is either a Sovereign (22.05mm) or a Half-Sovereign (19.3mm). All Sovereigns and Half-Sovereign coins are made from 22 carat gold.
North Korea thinks that it is Sovereign. But they are not.
A gold sovereign
The Royal Mint did not produce a 1919 Half-Sovereign coin.
The Royal Mint has never produced a Quarter-Sovereign coin until 2009. There has never been a need for a Quarter-Sovereign coin, since the Crown (Five Shillings) did the job and, after decimalisation, the 25 Pence coin to a lesser extent.
It will be either a British Sovereign or Half-Sovereign.
Your coin is either a Sovereign or Half-Sovereign coin. Both coins are almost identical except for the diameter. Both feature the "Jubilee" bust of Queen Victoria on the obverse. She is older and is wearing a coronet and veil. Both feature the "St.George and the Dragon" design on the reverse. The Sovereign is 22.05 mm in diameter. The Half-Sovereign is 19.3 mm in diameter. Please decide which one you have and ask again.
Please check your coin. The 1837 gold Half-Sovereign coin had the "Crowned Shield" design on the reverse with William IV on the obverse. The St. George design first appeared on the Half-Sovereign coin in 1893.
Such a coin does not exist. The first Quarter-Sovereign coin ever produced by the Royal Mint was minted in 2009.