Olives that will not be used to make oil must be harvested when they are completely ripe. Green olives are harvested when they go from green to light green in color.
First, the larger olives are harvested. The rest are collected as they grow larger. Black olives re harvested when they are properly darkened; when the meat of the fruit begins to take a violet color and before they get wrinkly. When the pit of the olive can be removed by squeezing one end of the olive, it means it’s ready to be harvested.
Brown, burgundy, or a lighter black color shows that an olive has been naturally fermented and flavored. An extraordinarily black color shows that dye has been used to artifically darken the olive.