Appearance
Each silver piece was marked with the number 8 and weighed approximately an ounce. This made it the largest and heaviest of the silver coins then in circulation.
Comparison
The British shilling was comprised of 1/20 an ounce of silver, with 20 shillings making up a British pound. This was equal to one Colonial dollar, or a piece of eight.
Change of 1816
In 1816, the English adopted the Gold Standard, lowering the value of silver drastically. The Guinea was withdrawn from usage, and the world began to base its currency on the pound instead of the Spanish miller.