The Lord is the reservoir of all pleasure. His auspicious presence is meant for everyone's benediction, and His affectionate smiling and glancing touch the core of the heart. The Lord's beautiful bodily color is blackish, and His broad chest is the resting place of the goddess of fortune, who glorifies the entire spiritual world, the summit of all heavenly planets. Thus it appeared that the Lord was personally spreading the beauty and good fortune of the spiritual world.
(Srimad Bhagavatam------3:15:39------translation).

Being very satisfied by the prayers of Dakṣa, Lord Viṣṇu appeared before Dakṣa with eight arms. The Lord was dressed in yellow garments and had a blackish complexion. Understanding that Dakṣa was very eager to follow the path of enjoyment, the Lord awarded him the potency to enjoy the illusory energy. The Lord offered him the daughter of Pañcajana named Asiknī, who was suitable for Mahārāja Dakṣa to enjoy in sex. Indeed, Dakṣa received his name because he was very expert in sex life. After awarding this benediction, Lord Viṣṇu disappeared.
(Srimad Bhagavatam------6:4:1-2------purport).

"Dear Lord," the demigods prayed, "when You appear in Your different incarnations, You take different names and forms according to different situations. Lord Kṛṣṇa is Your name because You are all-attractive; You are called Śyāmasundara because of Your transcendental beauty. Śyāma means blackish, yet they say that You are more beautiful than thousands of cupids. Kandarpa-koṭi-kamanīya. Although You appear in a color which is compared to that of a blackish cloud, You are the transcendental Absolute, and therefore Your beauty is many, many times more attractive than the delicate body of Cupid. Sometimes You are called Giridhārī because You lifted the hill known as Govardhana. You are sometimes called Nanda-nandana or Vāsudeva or Devakī-nandana because You appear as the son of Mahārāja Nanda or Devakī or Vasudeva.
(Srimad Bhagavatam------10:2:35------purport).

The color of the Lord's body is blackish, like that of a new cloud. Also, His body is very soft. Softness of the body is a sign of a great personality. The śāstras state that the following bodily features indicate a great personality: a reddish luster in seven places—the eyes, the palms, the soles, the palate, the lips, the tongue, and the nails; broadness in three places—the waist, the forehead, and the chest; shortness in three places—the neck, the thighs, and the genitals; deepness in three places—the voice, the intelligence, and the navel; highness in five places—the nose, the arms, the ears, the forehead, and the thighs; and fineness in five places—the skin, the hair on the head, the bodily hair, the teeth, and the fingertips. All these features are present in the body of the Lord.
The Brahma-saṁhitā confirms that the color the Lord's body is blackish, like that of a new cloud. But this blackish color is so beautiful that it surpasses the beauty of millions of Cupids. So this blackish color does not correspond to any blackish color in the material world.
(Mukunda-Mala-Stotra).

One gopī addressed her friend and began to praise the bodily features of Kṛṣṇa. She praised His blackish complexion, the reddish color of chewing pan enhancing His beauty hundreds of times, the curling hair on His head, the kuṁkum red spots on His body and the tilaka on His forehead.
(Nectar of devotion).

There is a similar statement by a devotee as follows: "I shall now begin my service of fanning the Supreme Personality of Godhead, Śrī Kṛṣṇa, who is seated on a golden throne. He is the supreme Parambrahma in His eternal transcendental form of a cloudy blackish complexion. Now I shall give up my affection for my material body, which is nothing but a bunch of flesh and blood." Herein also there is a combination of servitude and ghastliness, where the ecstasy of servitude is taken as the whole and the ecstasy of ghastliness is taken as the part.
(Nectar of devotion).

"Dear Lord, when You appear in Your different incarnations, You take different names and forms according to different situations. Lord Kṛṣṇa is Your name because You are all-attractive; You are called Śyāmasundara because of Your transcendental beauty. Śyāma means "blackish," yet it is said that You are more beautiful than thousands of Cupids (kandarpa-koṭi-kamanīya). Although You appear in a color which is compared to the blackish cloud, because You are the Transcendental Absolute, Your beauty is many, many times more attractive than the delicate body of Cupid."
(Krsna Book).

The brāhmaṇas' wives saw Kṛṣṇa with a blackish complexion, wearing a garment that glittered like gold. He wore a nice garland of forest flowers and a peacock feather on His head. He was also painted with the minerals found in Vṛndāvana, and He looked exactly like a dancing actor on a theatrical stage. They saw Him resting one hand on the shoulder of His friend, and in His other hand He was holding a lotus flower. His ears were decorated with lilies, He wore marks of tilaka, and He was smiling charmingly. With their very eyes the wives of the brāhmaṇas saw the Supreme Personality of Godhead, of whom they had heard so much, who was so dear to them, and in whom their minds were always absorbed. Now they saw Him eye to eye and face to face, and Kṛṣṇa entered within their hearts through their eyes.
(Krsna Book).