Answer:
In Biblical times Purple was a symbol of royalty and riches due to the scarcity of its dye.
There is slightly more to the meaning than the simple explanation given above. Look up the insect they used to create the color purple as a die for cloth.
Judges 8:26
The weight of the gold rings he asked for came to seventeen hundred shekels, not counting the ornaments, the pendants and the purple garments worn by the kings of Midian or the chains that were on their camels' necks.
Proverbs 31:22
She makes coverings for her bed; she is clothed in fine linen and purple.
Mark 15:20
And when they had mocked him, they took off the purple robe and put his own clothes on him. Then they led him out to crucify him
Mark 15:17
They put a purple robe on him, then twisted together a crown of thorns and set it on him.
Acts 16:14
One of those listening was a woman named Lydia, a dealer in purple cloth from the city of Thyatira, who was a worshiper of God. The Lord opened her heart to respond to Paul's message.
Revelation 17:4
The woman was dressed in purple and scarlet, and was glittering with gold, precious stones and pearls. She held a golden cup in her hand, filled with abominable things and the filth of her adulteries.
Purple in KJV biblical text
New Testament = 9 times Mark, Luke, John, Acts and Revelation
Old Testament = 39 times
Get a Strongs Concordance on line and look up the occurrences and actual meanings however, don't simply assume purple is a direct translation from Hebrew, Chaldee or Greek to English.