We need olives expert from HN - is this just USA (California) thing? I don't believe that black olives in Europe are actually artificially dyed with iron gluconate. My impression is that in Europe black olives are riped olives picked in late autumn or winter. Anyone to confirm?
Not an olive expert, but in Croatia (and probably the rest of Europe - Mediterranean) AFAIK green olives are picked in autumn, and black ones, that is full ripe ones, are picked in November and December. Those olives are used for the production of olive oil and they give the oil it's distinct golden colour... honestly, colouring olives sounds awful.
