If you mean a green circle or greenish ring around the yolk of a hard-boiled egg, it usually means the egg was overcooked or cooled too slowly.
The ring forms when sulfur from the egg white reacts with iron in the yolk, producing iron sulfide. 🥚
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Is it safe? Yes. The green ring itself isn’t a sign that the egg is spoiled.
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Does it mean the egg is old? Not necessarily. Cooking time and temperature are the main causes.
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How to prevent it: Don’t overcook the eggs, and cool them promptly in cold/ice water after cooking.
If you’re referring to a green circle printed on an eggshell, carton, or egg itself, send me a photo—that can mean something completely different.
