Beautiful art appreciated with a high note from NGC MS66.
The 10- and 20-gold with the image of King Boleslaw the Brave is a design by Zofia Trzcinska-Kaminska, selected in a 1925 competition. The first gold coins were minted in 1926, albeit with a date commemorating the 900th anniversary of Chrobry's coronation. They were made in accordance with the first monetary reform of the Second Republic, but due to the value of gold being higher than the denomination of the coins, they were not put into circulation.
Gold, diameter 19 mm, weight 3,225 g (catalog).