Ancient Greek coins had three values, the metallic, the nominal and the commercial. 
Their metallic value depended on their metal content, and was high when they were gold, lower when they were silver and much lower when they were copper. 
The gold-silver ratio was initially 1:12, and this affected the monetary parities between the two metals. 
By 400 BC, coins became the predominant means of exchange throughout ancient Greece, but without imposing a specific currency. 
Simply, in each region they used a specific currency more than the others. 
Over time, the Attic Tetradrachm, weighing 17 grams, began to prevail, with subdivisions (1/6 drachma = 1 obol), and multiples (decadrachma), while in the Sicilian colonies the liter coin was also used.

At the same time, the artistic processing of the coins evolved, which were now decorated with various figures of gods and animals. 
They were minted with the help of a hammer and anvil (by striking), which is why many of the coins of this era do not have a perfect image, 
while their shape is not always exactly round.