Color of 64-Across Crossword Clue

 The answer to the crossword clue "color of 64-Across" is RED.

The 64-Across clue is "Color that can appear after the first word of 16-, 27-, 48-and 60-Across". The first words of those clues are "blood", "crimson", "scarlet", and "ruby". All of these words are associated with the color red.

Here are some other possible answers for the crossword clue "color of 64-Across":

VIOLET

ORANGE

YELLOW

GREEN

BLUE

However, the clue specifically mentions that the color can appear after the first word of the other clues. None of the other colors can appear after the first word of those clues. Therefore, the only possible answer is red.