Matrices of a given size with entries from a field form an associative
algebra, and can therefore be considered as a Jordan algebra. From th
at point of view, the determinant of a matrix is nothing but the reduc
ed generic norm of the Jordan algebra. The basic expansion formulas of
matrix determinants along a row or column do not make sense in the se
tting of arbitrary Jordan algebras. However, there also exists an expa
nsion formula for matrix determinants along the diagonal of a matrix.
In the paper, we show that, suitably interpreted, such an expansion fo
rmula holds for the reduced generic norm of a large class of Jordan al
gebras, including separable finite-dimensional Jordan algebras over fi
elds of characteristic not 2.