Guinea (coin)

The guinea is a coin of approximately one quarter ounce of gold that was minted in the Kingdom of England and later in the Kingdom of Great Britain and the United Kingdom between 1663 and 1814. It was the first English machine-struck gold coin, originally worth one pound sterling, equal to twenty shillings, but rises in the price of gold relative to silver caused the value of the guinea to increase, at times to as high as thirty shillings. From 1717 to 1816, its value was officially fixed at twenty-one shillings. Then, Great Britain adopted the gold standard and guinea became a colloquial or specialised term.