That is, if the player has a Queen available, the Queen becomes the new King. If no Queen is available, but a Rook is available, a Rook becomes the new King, etc.
If a player has two (2) or more Queens, Rooks, Bishops or Knights, he may choose which one ascends to the throne.
This list obviously assumes the players are using FIDE chess movements and rules. Players using variant pieces (Camels, Dabbabahs, Yawns, etc.) should agree beforehand on the order of ascension.