Blue

(5) they, therefore, shall receive the gold, the blue, purple, and crimson yarns, and the fine linen. (6) They shall make the ephod of gold, of blue, purple, and crimson yarns, and of fine twisted linen, worked into designs. (7) It shall have two shoulder-pieces attached; they shall be attached at its two ends.

(28) The breastpiece shall be held in place by a cord of blue from its rings to the rings of the ephod, so that the breastpiece rests on the decorated band and does not come loose from the ephod. (29) Aaron shall carry the names of the sons of Israel on the breastpiece of decision over his heart, when he enters the sanctuary, for remembrance before יהוה at all times. (30) Inside the breastpiece of decision you shall place the Urim and Thummim, so that they are over Aaron’s heart when he comes before יהוה. Thus Aaron shall carry the instrument of decision for the Israelites over his heart before יהוה at all times. (31) You shall make the robe of the ephod of pure blue.

(37) יהוה said to Moses as follows: (38) Speak to the Israelite people and instruct them to make for themselves fringes on the corners of their garments throughout the ages; let them attach a cord of blue to the fringe at each corner. (39) That shall be your fringe; look at it and recall all the commandments of יהוה and observe them, so that you do not follow your heart and eyes in your lustful urge. (40) Thus you shall be reminded to observe all My commandments and to be holy to your God. (41) I יהוה am your God, who brought you out of the land of Egypt to be your God: I, your God יהוה.

It is taught in a baraita that Rabbi Meir would say: What is different about tekhelet from all other types of colors such that it was chosen for the mitzva of ritual fringes? It is because tekhelet is similar in its color to the sea, and the sea is similar to the sky, and the sky is similar to the Throne of Glory, as it is stated: “And they saw the God of Israel; and there was under His feet the like of a paved work of sapphire stone, and the like of the very heaven for clearness” (Exodus 24:10), indicating that the sky is like a sapphire brickwork. And it is written: “The likeness of a throne, as the appearance of a sapphire stone” (Ezekiel 1:26).

From when does one recite Shema in the morning? From when a person can distinguish between sky-blue [tekhelet] and white.
Rabbi Eliezer says: From when one can distinguish between sky-blue and leek-green.
And one must finish reciting Shema until the end of the period when you rise, i.e., sunrise, when the sun begins to shine.
Rabbi Yehoshua says: One may recite the morning Shema until three hours of the day, which this is still considered when you rise, as that is the habit of kings to rise from their sleep at three hours of the day. While there is a set time frame for the recitation of Shema, one who recites Shema from that time onward loses nothing. Although he does not fulfill the mitzva of reciting of Shema at its appointed time, he is nevertheless considered like one who reads the Torah, and is rewarded accordingly.