The stars shine like diamonds

Meaning: This means the same as the first two sentences, but it emphasizes that we are talking about the stars in particular.

Choice of Words: The is a definite article that refers to a specific noun. In this case, it refers to the stars. Shine means to give off light. Diamonds are shiny stones that are often used in jewelry. So, "The stars shine like diamonds" means that the stars give off light in a way that is similar to how diamonds reflect light.