List four criteria used in grading eggs.

1. Shell quality: The shell should be clean, unbroken, and free from cracks or blemishes.
2. Yolk color: The yolk should be a rich, deep yellow or orange color, indicating a high level of nutrients.
3. Albumen quality: The egg white should be clear and viscous, with no signs of blood spots or discoloration.
4. Size: Eggs are graded by weight, with larger eggs typically receiving a higher grade.

1. Shell quality
2. Air cell size
3. Albumen quality
4. Yolk quality