Dear Sandya,
I have found this description of Krishna's colour:
"The colour of the Original Personality of Godhead viz. Krishna/Shyamasundara is described as follows:
Sri Brahma-Samhita 5.30
In reply to:
--
I worship Govinda, the primeval Lord, who is adept in playing on His flute, with blooming eyes like lotus petals with head decked with peacock's feather, with the figure of beauty tinged with the hue of blue clouds, and His unique loveliness charming millions of Cupids.
PURPORT
The matchless beauty of Krishna, the Supreme Lord of Goloka, is being described. Krishna, the all-pervading cognition, has a spiritual form of His own. The form of Krishna is not a fanciful creation of imagination formed after visualizing the beautiful things of the world. What Brahma saw in his ecstatic trance of pure devotion, is being described. Krishna is engaged in playing upon His flute. That flute by his enchanting musical sound attracts the hearts of all living beings. Just as a lotus petal produces a pleasant sight, so the two beautiful eyes of Krishna who causes the manifestation of our spiritual vision, display the unlimited splendor and beauty of His moonlike face. The loveliness that adorns His head with peacock feather figures, the corresponding feature of the spiritual beauty of Krishna. Just as a mass of blue clouds offers a specifically soothing, pleasant view, the complexion of Krishna is analogously tinged with a spiritual dark-blue color. The beauty and loveliness of Krishna is far more enchanting that that of Cupid multiplied a millionfold.
--
Sri Brahma-Samhita 5.38
In reply to:
--
I worship Govinda, the primeval Lord, who is Syamasundara, Krishna Himself with inconceivable innumerable attributes, whom the pure devotees see in their heart of hearts with the eye of devotion tinged with the salve of love.
PURPORT
The Syamasundara form of Krishna is His inconceivable simultaneous personal and impersonal self-contradictory form. True devotees see that form in their purified hearts under the influence of devotional trance. The form Syama is not the blue color visible in the mundane world but is the transcendental variegated color affording eternal bliss, and is not visible to the mortal eye. On a consideration of the trance of Vyasadeva as in the sloka, bhakti-yogena manasi etc., it will be clear that the form of Sri Krishna is the full Personality of Godhead and can only be visible in the heart of a true devotee, which is the only true seat in the state of trance under the influence of devotion. When Krishna manifested Himself in Vraja, both the devotees and nondevotees saw Him with this very eye; but only the devotees cherished Him, eternally present in Vraja, as the priceless jewel of their heart. Nowadays also the devotees see Him in Vraja in their hearts, saturated with devotion although they do not see Him with their eyes. The eye of devotion is nothing but the eye of the pure unalloyed spiritual self of the jiva. The form of Krishna is visible to that eye in proportion to its purification by the practice of devotion. When the devotion of the neophyte reaches the stage of bhava-bhakti the pure eye of that devotee is tinged with the salve of love by the grace of Krishna, which enables him to see Krishna face to face. The phrase "in their hearts" means Krishna is visible in proportion as their hearts are purified by the practice of devotion. The sum and substance of this sloka is that the form of Krishna, who is Syamasundara, Natavara (Best Dancer), Muralidhara (Holder of the Flute) and Tribhanga (Triple-bending), is not a mental concoction but is transcendental, and is visible with the eye of the soul of the devotee under trance.
--
Sometimes Krishna is shown blackish and at other time bluish which more resembles the transcendental colour of His Narayana form; in His Original Form of Krishna (Shyamasundara) the color is compared to that of a cloud and is thus bluish-black; these colors appear to us as material "approximations" of the originals in neophyte stages. "
Hope, this clears it. Hare Krishna!
