Ripe Oxidized black olives (California style )

They are not naturally ripe and their colour -intensely black- comes from an industrial oxidation process where typically green olives are subject to strong alkaline treatments and exposed to iron salts, then packed in specific tins such as A10 & A12 tins then be sterilized in autoclave.

Ripe black olives may be :
(a) whole black olives
(b) sliced black olives
(c) pitted black olives