i just wrote this!

ha.cs

using UnityEngine;

public class _Ha : MonoBehaviour {

  float red = 0x00;
  float green = 0x00;
  float blue = 0x00;
  const int step = 1;
  const int min = 0x08;
  const int max = 0xFF;


  void Update () {

    red += step;

    red %= ( red % max == 0 ) ? min : max;

    Color color = new Color(red / 0xFF, green / 0xFF, blue / 0xFF, 1);

    gameObject.renderer.material.color = color;

  }
}