I've looked at various pictures, and at times you can tell it's blue (like this one) and at times it has a purpley cast to it. Probably one of those darn colors that looks different depending on the light.
the president has dozens of ties in the same color
https://kstp.com/coronavirus/president-trump-and-first-lady-test-positive-for-covid-19/5881446/
Looks purple here.