Watch List notes:

Koninkrijk NL Willem III (1849-1890) - ½ Gulden 1850 (Sch. 622 /RRR), extremely rare date. According to the online Handboek Laurens Schulman (LSch. 502) the mintage was just a few specimens. Struck with polished dies = Proof. Lightly cleaned, XF+. Generally considered one of the rarest Kingdom coins of The Netherlands.