Blue is popular in Scripture and the favorite of most people around the world. More than half of the countries on earth have it in their national flags. This includes countries such as Australia, France, Israel, North Korea, Netherlands, the United States and others. Though representing a group of countries, the flag of the European Union has a blue background.
Variations of blue exist in churches decorated during the period of the Byzantine Empire (395 to 1204 and 1261 to 1453 A.D.). In the Islamic world, it is second only to green in importance, which some believe to have been the favorite of Mohammed. It is the most common color found in the logos of modern corporations. It also designates, in many cultures, that the sex of a newborn baby is male.
Owing to its popularity, the major professional baseball, basketball, football and hockey leagues in the United States all have this coloration as part of the league's official logo.
In the KJV Bible, the word 'blue' occurs fifty times, all of which are in the Old Testament. The Hebrew word translated as this color is tekeleth (Strong's Concordance #H8504), which is a reference to the animal from which the dye is obtained. Its meaning in Scripture is that of representing God (Exodus 24:10, 25:3, 38:18, Numbers 4:6 - 12, 2Chronicles 2:7, Ezekiel 1:26, etc.), royalty (Esther 1:6, Ezekiel 23:6, Jeremiah 10:9), riches (Ezekiel 27:7, 24) or service to God and godly living (Exodus 28:6, 8, 13, 31, Numbers 15:38 - 40, Esther 8:15).
Several Biblical commentaries state that the liquid from which blue dye originated came from a shellfish native to the Mediterranean Sea. The possibly also exists it was extracted from the rind of pomegranates. The process of using it for dyeing entailed soaking clothe in dye vats and then letting them dry. This process was repeated several times until arriving at the desired color. The final step was soaking the cloth in a solution that would render the cloth colorfast.
Additional info on Biblical Meaning of blue
Moses, Aaron, two of Aaron's sons, and the seventy elders of Israel went up Mount Sinai to worship God before he gave the Israelites the Ten Commandments in stone (Exodus 24). The Bible states they not only saw God but also noticed that under his feet was some sort of pavement made of Sapphires.
And they saw the God of Israel. And there was under His feet as it were a paved work of a sapphire stone, and as it were the heavens in clearness (Exodus 24:10, HBFV).
Sapphires, one of the many gemstrones mentioned in Scripture, is referenced nine times in God's word. The gem reflects a beautiful sky color.
Sapphires are also found on the 'breastplate of judgment' sometimes worn by the High Priest (Exodus 28:18). This blue gem was one of several that God personally placed as ornamentation on Lucifer when he created him (Ezekiel 28:13). This stone, according to the Bible, will soon be used to decorate one of the twelve foundations God will create for the New Jerusalem (Revelation 21:19).