Albert Barnes Commentary Esther 8:15

"And Mordecai went forth from the presence of the king in royal apparel of blue and white, and with a great crown of gold, and with a robe of fine linen and purple: and the city of Shushan shouted and was glad." — Esther 8:15 (ASV)

See the Esther 1:6 note. The “crown” was not a crown like the king’s, but a mere golden band or coronet.

A garment—or, “an inner robe.” The tunic or inner robe of the king was of purple, striped with white.