Jamieson, Fausset and Brown on Esther 2:17

17. the king loved Esther above all the women--The choice fell on Esther, who found favor in the eyes of Ahasuerus. He elevated her to the dignity of chief wife, or queen. The other competitors had apartments assigned them in the royal harem, and were retained in the rank of secondary wives, of whom Oriental princes have a great number.

he set the royal crown upon her head--This consisted only of a purple ribbon, streaked with white, bound round the forehead. The nuptials were celebrated by a magnificent entertainment, and, in honor of the auspicious occasion, "he made a release to the provinces, and gave gifts, according to the state of the king." The dotation of Persian queens consisted in consigning to them the revenue of certain cities, in various parts of the kingdom, for defraying their personal and domestic expenditure. Some of these imposts the king remitted or lessened at this time.