The two guineas, or double guinea, is a coin of approximately one half of an ounce of gold that was minted in the Kingdom of England and later in the Kingdom of Great Britain between 1664 and 1753 (after that, trials were produced until 1777). The name comes from the Guinea region in West Africa, where much of the gold used to make the coins originated.
This was one of the first English machine-struck gold coins, originally forty shillings (two pounds); 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 (so, two guineas were worth 60 shillings); from 1717 until 1816, its value of the guinea was officially fixed at twenty-one shillings.
The designs of the coins, as was typical of the period, are generally exactly the same as those of other denominations and, given that their values are not inscribed on the coins, the inscriptions are the same too. Thus, coins issued at the same time look virtually the same and the different denominations can only be distinguished by their composition and size.
The guinea denominations were demonetised with the recoinage of 1816. | 
