Vajrasattva is pure white in colour and is sometimes known as the Prince of Purity. His name means “Adamantine Being”, or more poetically “Embodying Reality”. He is a member of the Vajra family of Akṣobhya which also includes Vajrapāṇi.

He is depicted as a young man in the prime of life, with all the silks and jewels of a wealthy prince. In his right hand he delicately balances a vajra at his heart. In his left had he holds a bell at his waist. The vajra represents Reality, and Compassion; while the bell represents Wisdom.

In some mandalas Vajrasattva represents the Ādibuddha or the Primordial Principle of Buddhahood; in others he changes places with Akṣobhya in the East. In Shingon Buddhism it is Vajrasattva that passes on the initiation of the Dharmakāya Buddha Mahāvairocana to Nāgārjuna, thereby creating the Vajrayāna lineage.

via Vajrasattva Mantra – 100 Syllable Vajrasattva mantra and short Vajrasattva mantra..