As your shirt is white, the standard plain white slash might be a bit stark. I mean, it would be OK, but not perfect. As the tie is so strong, I think you could even go with a softer, darker blue PS to rein it in a bit. Otherwise, burgundy always makes a sweet contrast with blues IMO. That looks like an outstanding suit, by the way.
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Thanks, Mimo. My thoughts exactly on the white linen and I have a conspicuous gap in darker blue/reds to fill in.