The collar is the same material as the shirt, navy knit pique. Specifications were:
7" pullover placket with 3 buttons.
Collar: 1.75" back height and 3.5" point length.
Soft collar but with a stiff neckband.
Note: this was the linen-cotton blend, which shrank like a mo-fo in the wash. The material feels fantastic, though, very luxurious. If you opt for this either keep it away from warm water or account for shrinkage in your measurements.