So, how do you know when those eggs are finally done? Well, here are a few signs to look out for: the eggs will be firm to the touch, the yolks will be cooked through, and the whites will be set. You can also try spinning the egg on the counter - if it spins smoothly, it's cooked, but if it wobbles, it needs a bit more time!
How Do I Know If A Boiled Egg Is Done at Thomas Schnell blog
And, let's not forget about the color! When eggs are cooked, the yolks will be a beautiful yellow color, and the whites will be white (obviously!). If the yolks are still runny or the whites are pinkish, they need a bit more cooking time.
