Wonder Boy in Monster Land/Enemies

While some enemies only take one hit to kill, many of the enemies require a more concerted effort to defeat. Many such enemies have a jewel visible somewhere on their bodies. This jewel reflects the state of their health. The jewel goes through several colors as you weaken the enemy. A red jewel means the enemy is close to defeat, while a blue jewel means the enemy is quite healthy. A blue jewel will progress through cyan, green, yellow, and orange before turning red. An enemy with a blue jewel may take many hits before the jewel even begins to show any sign of changing colors. This does not mean you are not hurting the enemy; it merely means you have not hurt the enemy enough to change the color of the jewel yet.