In 1927 Netherlands Post issued 7½c violet denomination stamp, featuring syncopated perforation Type D. This is one of the rarest of all Netherlands issues. It is also one of the most challenging stamps in all of Netherlands. A wonderfully well centered, very fine, the rarest of the syncopated perf varieties of 1927 7½c violet denomination stamp was sold at H.R. Harmer auction in May, 2014. Signed Koopman, this extremely rare and very desirable stamp managed to fetch $3,000.