Here are some examples of how it's used:
* De quelle couleur est ta voiture ? (What color is your car?)
* De quelle couleur sont tes yeux ? (What color are your eyes?)
* De quelle couleur est le ciel aujourd'hui ? (What color is the sky today?)
It's important to note that "de quelle couleur" is used when asking for a specific color. If you are just asking about the general color of something, you can use "quelle couleur".