SB 3.28.13

prasanna-vadanāmbhojaṁ
 padma-garbhāruṇekṣaṇam
nīlotpala-dala-śyāmaṁ
 śaṅkha-cakra-gadā-dharam
Word for word: 
prasanna — cheerful; vadana — countenance; ambhojam — lotuslike; padma-garbha — the interior of a lotus; aruṇa — ruddy; īkṣaṇam — with eyes; nīla-utpala — blue lotus; dala — petals; śyāmam — swarthy; śaṅkha — conch; cakra — discus; gadā — club; dharam — bearing.
Translation: 
The Supreme Personality of Godhead has a cheerful, lotuslike countenance with ruddy eyes like the interior of a lotus, and a swarthy body like the petals of a blue lotus. He bears a conch, discus and mace in three of His hands.
Purport: 

It is definitely recommended herein that one concentrate his mind upon the form of Viṣṇu. There are twelve different forms of Viṣṇu, which are described in Teachings of Lord Caitanya. One cannot concentrate his mind on anything void or impersonal; the mind should be fixed on the personal form of the Lord, whose attitude is cheerful, as described in this verse. Bhagavad-gītā states that meditation on the impersonal or void features is very troublesome to the meditator. Those who are attached to the impersonal or void features of meditation have to undergo a difficult process because we are not accustomed to concentrating our minds upon anything impersonal. Actually such concentration is not even possible. Bhagavad-gītā also confirms that one should concentrate his mind on the Personality of Godhead.

The color of the Personality of Godhead, Kṛṣṇa, is described here as nīlotpala-dala, meaning that it is like that of a lotus flower with petals tinted blue and white. People always ask why Kṛṣṇa is blue. The color of the Lord has not been imagined by an artist. It is described in authoritative scripture. In the Brahma-saṁhitā also, the color of Kṛṣṇa’s body is compared to that of a bluish cloud. The color of the Lord is not poetical imagination. There are authoritative descriptions in the Brahma-saṁhitā, Śrīmad-Bhāgavatam, Bhagavad-gītā and many of the Purāṇas of the Lord’s body, His weapons and all other paraphernalia. The Lord’s appearance is described here as padma-garbhāruṇekṣaṇam. His eyes resemble the inside of a lotus flower, and in His four hands He holds the four symbols: conchshell, discus, mace and lotus.