Why Does a Green Ring Appear Around Hard-Boiled Eggs?

Why It Happens

When eggs are boiled too long or at too high a temperature:

Sulfur from the egg white reacts with iron in the yolk.

This forms ferrous sulfide, which appears as a green or gray ring around the yolk.

🍳 How to Prevent It

1. Don’t overcook:
   Boil eggs gently for 9–12 minutes (depending on size).
2. Cool quickly:
   After boiling, immediately place the eggs in cold water or an ice bath for 5–10 minutes.
3. Use fresh eggs:
   Older eggs can develop rings more easily because their pH is higher.

🥚 Is It Safe to Eat?

Yes — the eggs are completely safe to eat. The ring only affects appearance, not taste or nutrition.