A challenging search but my information was taken from this link:
http://finds.org.uk/news/theyworkfo.../COIN+WEIGHT"A Post Medieval copper alloy square coin weight for a rose ryal of James I dating 1603-1625. In 1612 the rose ryal value was increased from thirty to thirty-three shillings, this coin weight is to check the weight of the revalued ryals. Obverse: a shield of royal arms within a rose Reverse: XXXIII with crown above and 's' below. Dimensions: length: 20.31mm; width: 20.73mm; thickness: 4.36mm; weight: 13.34g."