Painting "White" in Watercolor

In watercolor, we use color to interpret the "white" in a subject. The colors we choose, the temperature of the color, whether we use a compliment, or a "gray" neutral, all affect the mood of the painting and how our eyes see the "white". Below are three watercolor sketches I demonstrated for a beginning techniques workshop.
In this little painting, the "white" is cool pink. I used a warm neutral green to compliment the cool pink.

For this painting, I used a cool green as the half-tone (next to lightest color) to compliment the pink.

Here, the yellowish white and cool violet describe the white form.

All the paintings above were done with the same pigments; Aureolin Yellow, Rose Madder Genuine, New Gamboge/ Quin Gold, Viridian, and Winsor Violet