Percy

Sea green

This is a clear, bright and luminous, intense, gorgeous, blue-green color that sometimes has a darker blue rim around the outer part of the iris. It's a very pretty eye-color and can be sharpened with specific description.

Annabeth

Stormy grey eyes

Her eyes are startling, fierce, luminous, intense, steely, medium- to pale true-gray (by true, I mean an equal ratio of blue and white rays in the iris so that its color appears to be only gray with no hints of blue). Cloud gray has additional connotations of dreaminess, melancholy, and moodiness. Her eyes have "cloud" connotation that includes the passion and drama of a storm. Storms can color the clouds and sky black, gray, or even a sulfur-yellow. Her eyes reflect the colors in the background or what she sees. They also have a distracted look like she is thinking a million things at once.

 

Piper-

Eyes that change color like a kaleidoscope going from brown to blue to green. They are described as very pretty, distracting and beautiful.

Hazel

gold eyes or amber

Her eyes are startling, glittering, luminous warm gold color. They are like fourteen-karat gold.  Golden sounds rich and beautiful and has a pleasing sound.

Jason

electric blue eyes or sky blue or icy blue

His eyes are a clear, startling, piercing light blue like the summer sky seen in the desert at noon. These are extremely pale blue eyes that are colder and not as delicate as crystal-blue eyes. They are a pale to medium bright-blue. They are a true-blue (no overtones from other colors in the spectrum) and are extremely bright, energetic, and striking.