Bold X Sudoku

Bold X Sudoku is a variation of the Sudoku X puzzle. Each marked diagonal of this puzzle must contain non-repeating numbers.

Rules: In each cell of the 9×9 grid, enter a number in the range 1–9. Each number must appear exactly once in each row, column, and block.
Additional rules: The numbers on all marked diagonals (resembling a bold letter X) must be different.