Do colors have a specific symbolic meaning in the Torah? (For ex. is it brought down anywhere that blue is holy?)
According to the Jewish Encyclopedia:
(a) It has been generally assumed that at times colors are used in the Bible symbolically, either in the ritual, as in the construction of the Tabernacle and in the priestly raiments; or apocalyptically, as in the visions of Zechariah and of Daniel; or, as a literary device, in poetical diction. Philo ("De Vita Mosis," iii. 6) and Josephus ("Ant." iii. 7, § 7) attempted to explain the ritual symbolism of colors, but without convincing force (see, also, Baehr, "Symbolik des Mosaischen Kultus," Heidelberg, 1874). The apocalyptic symbolism is admitted more generally; yet it fails when tested in detail. Literary symbolism, however, based on a psychological connection between the various color-sensations and moods of feeling, is found among most nations. Yet the relations between a given color and the symbolized objects or moods are not fixed; and they leave room for difference of explanation.
Black or dark color points to mourning or affliction (II Sam. xix. 24; Zech. vi. 6, 8); such was probably also the color of sackcloth used in mourning. On the other hand, white suggests purity (Isa. i. 18; Ps. li. 9) and joy (Mishnah Mid. v. 4). Scarlet or red is symbolical of bloodshed, of sin in general (Isa. i. 15, 18; lxiii. 1), and, in the opinion of some commentators, of vigorous life (Lev. xiv.; Num. xix.). Purple-red denotes royalty and royal splendor (Judges viii. 26; Esth. viii. 15; Dan. v. 7). Purple-blue, used for fringes in the garment of every Israelite (Num. xv. 38), is thought, on the one hand, to symbolize the high dignity of every member of the people of the covenant (compare Ex. xix. 6); and, on the other, to suggest the God of heaven (Gen. xxiv. 7; Ps. xi. 4), because of the same color as the sky.
(b) Color-symbolism plays a great part in the Cabala, where to each Sefirah are attributed one or more colors; and one who wishes to energize the influence of a certain Sefirah has to contemplate, or clothe himself in, the particular color attributed to that Sefirah. White signifies peace, mercy, and pity; black, latency of qualities; red, bloodshed, cruelty, and justice; azure, attributed to the Sefirah of wisdom, is said to denote the first step from black (latency) to the development of color—that is, active energy in general; saffron-color or yolk-yellow is considered a combination of red and white; green is said to be a combination of red, white, and azure; purple-red, a compound of all colors; golden yellow symbolizes cheering, justice, etc.
"Speak to the Children of Israel and bid them that they make fringes on the corners of their garments throughout their generations, and that they put upon the fringe of each corner a thread of blue (tekhelet). And it shall be for you as a fringe, that you may look upon it and remember all the commandments of G-d, and do them..." (Numbers 15:38-39)
Suppose Blue (tekhelet) is therefore considered holy