The Guinea is a famous British gold coin minted between 1663 and 1814. The coin was originally created as a one pound coin (20 shillings) but is better known as being worth One Pound and One Shilling (21 shillings).
After the English Civil War, King Charles II introduced new coinage. A gold coin, approximately a quarter of an ounce, was issued and for the first time it was not hammered. Made by machine using gold from the Guinea Coast of West Africa the coin probably became the most important coin of the realm.
Originally 20 shillings, the coin actually fluctuated with the gold price, at times being as high as 30 shillings. In 1717 the Guinea became fixed at 21 shillings (in today’s money that is £1.05). Other coins of the family were also minted, such as half-guinea, two-guinea and five-guinea.
In the Great Recoinage of 1816 the Guinea was replaced by the Pound and the Sovereign became the gold coin in use. Long after the Guinea was retired the name continued to be used, especially for prestige purchases intended for the more wealthy. Even now racehorses are still sold in Guineas (the auctioneer traditionally taking the 5p as commission).
Guineas are 25mm in diameter, weigh about 8.38g and are 22 carat gold (91.6%). Prior to 1717 they weighed slightly less (around 8.3g) and were made of 91.34% gold.
On eBay UK:
 | 1903 Gold Half Sovereign Edward VII £ 285.00 |
 | 9ct Yellow Gold on Silver Sovereign Coin Ring - ALL SIZES AVAILABLE inc LARGE £ 29.95 |
 | gold sovereign pendant 1822 £ 1,600.00 |
 | 2018 Proof GOLD QUARTER SOVEREIGN FALKLANDS Anniversary Gibralta £ 180.00 |
 | 1892 FULL SOVEREIGN COIN 22 ct GOLD VICTORIAN £ 575.00 |
 | 1847 FULL SOVEREIGN COIN 22 ct SOLID GOLD VICTORIAN Shield £ 575.00 |
 | 2010 BRITISH SOVEREIGN 22CT GOLD PLATED LARGE COIN QUEEN ELIZABETH II £ 12.99 |
 | 22ct gold quarter sovereign coin £ 175.00 |
On eBay USA:
| 1903 Gold Half Sovereign Edward VII £ 285.00 |
| 9ct Yellow Gold on Silver Sovereign Coin Ring - ALL SIZES AVAILABLE inc LARGE £ 29.95 |
| 2010 BRITISH SOVEREIGN 22CT GOLD PLATED LARGE COIN QUEEN ELIZABETH II £ 12.99 |
| 2018 Proof GOLD QUARTER SOVEREIGN FALKLANDS Anniversary Gibralta £ 180.00 |
| 1847 FULL SOVEREIGN COIN 22 ct SOLID GOLD VICTORIAN Shield £ 575.00 |
 | 1974 Full Gold Sovereign coin. Queen Elizabeth II £ 540.00 |
 | SCARCE 1878 S SYDNEY Victoria SHIELD Full Gold Sovereign AUSTRALIA #56 £ 675.00 |
| 22ct gold quarter sovereign coin £ 175.00 |