Vajra-sattva means Diamond-being, or Divine Being and as the one Primordial Buddhas, represents the Absolute. This practice was taken from Kunzang Palden Rinpoche's booklet, "Awakening the Core of Being."

Upon going to sleep at night, visualize a tiny circular double-sided mirror, not much bigger than a mustard seed and flat like a plate, inside your heart. From the center of the surface of this mirror there radiates a sapphire blue light. From the front region of the mirror there radiates a crystal white light. From the right side of the mirror there radiates amber light. From the back of the mirror there radiates ruby red light. From the left side of the mirror there radiates emerald green light. These five prismatic radiances (or "rainbow rays")correspond to the mantric sounds of: OM (front), VAJRA (right), SAT(behind), TVA (left) and HUM (center).

As you repeat to yourself the mantra OM VAJRA SATTVA HUM, imagine the rays of the lights emanating outwards, like rainbows filling the whole world. Thus the whole world is permeated with the grace-waves of the Buddha-mind. You can imagine the Sanskrit symbols for these mantric sounds also. Then gradually dissolve all the lights and the whole world back into the central blue light, corresponding to the eternal harmonious vibration HUM. (That is, imagine that the emanated rays, enriched by manifold blessing and love, are re-absorbed back into your heart.)

As you pass into unconsciousness, keep your attention on the pure blue light of the HUM-vibration for as long as possible. Each morning, as soon as waking, immediately remember that your intrinsic nature is translucent nondual Buddha-mind (Vajrasattva). It is also good to remember and record your dreams. With the development of this practice, your dreams will reveal much about both your negative and positive states, and the progress you are making on the Path.