The bishop usually wears a golden crown during prayer as did the twenty-four heavenly priests (Rev. 4:4).
This crown reminds us of the heavenly crown as well as Christ's crown of thrones.
It is also symbolic of the authority given by the Lord to His high priest (2 Cor. 10:8), by which a patriarch becomes the steward of the secrets of Christ (1 Cor. 4:4).
All through the previous generation deacons used to wear white crowns (caps) ornamented by icons and crosses, while they were praying the Liturgy of the Eucharist.
Dictionary of church terms. — St. GEORGE'S COPTIC ORTHODOX CHURCH SPORTING - ALEXANDRIA EGYPT. Fr. Tadros Yacoub Maiaty.