In 1663, the Royal Mint of England made a special gold coinage of twenty-shilling pieces “in the name and for the use of the Company of Royal Adventurers of England trading with Africa.”
These coins, and others of the same value afterward coined for general use, were called guineas, because the trade of the “Royal Adventurers of England” was actually along the coast of Guinea.
At this period in English history the standard of value was not gold, but silver, and the silver coinage was in bad state owing to the activities of “clippers,” who mutilated coins by paring the edges.
The value of the gold guinea therefore increased to more than twenty-shillings’ worth of silver coin, or more than its face value. Accordingly, in 1717, its value was fixed at 21 shillings.
After the establishment of the gold standard in 1816 no more guineas were coined.