If you thought that stone currency was unique to the Micronesian island of Yap think again. Coins made of slate were in use the Welsh principality of Gwynedd from over 1000 years ago. Not the small change that you can carry in a codpiece, these were up to 8 foot diameter and capable of causing serious damage when you put together round objects, hilly landscapes and gravity. One documented tragedy occurred at a Crusades recruitment drive in Blaenau. During Medieval Times, with the evolution of a new middle class, smaller thinner slate coins came into everyday use, with a variety of names and values for the many different sizes in use. Value of the slate pieces could also depend on the colour of the slate and how chipped the edges were. Eventually these became square or oblong and people would display their wealth by using them to keep the rain out of their homes. Even today a so-called Dowry Cottage is sought out by homebuyers.
The stamps show slate coins in use throughout the centuries. The picture of Castel de Bere shows giant slate coins propped up on the walls (before they were nicked). The next stamp shows Prince of Gwynedd Hywell Dda collecting taxes. The minstrels, Bywyd Orllewin the must-see act of their time, are at the court of Llewellyn the Great with their appearance money. In the view of Caernarfon on market day several people can be seen with their slate coins. The two masons are synchronised minters, as illustrated by their headgear, chipping out new coins. And finally one stamp shows a row of Dowry Cottages.