Queen Wilhelmina celebrated her Silver Jubilee in 1923. Luckily, this was at a time when the Dutch overseas territories still very much went their own way as far as stamp designs was concerned. We therefore have different sets for the Netherlands, the Netherlands Indies, Curaçao and Surinam. The stamps for the three territories have the same portrait (which differs from the Dutch portrait) but various frames. The portrait on these stamps was designed by H. Cheffer, based on a photograph by court photographer H. Deutmann. The frames were designed by H. Seegers. The stamps were recess-printed by Enschedé. Here's an example of the Curaçao set.
I like these very much for they have an old-fashioned feel, and seem fit for such a royal occasion. I'm obviously not the only one, for the sets are quite popular and (especially the high values) rather expensive. And you have to dig even deeper into your wallet because the Curaçao set comes with two perforation types: line perf 11 x 11.5 and line perf 11.5.
Oh well, one down, many to go!