[from my private collection]:

300th ANNIVERSARY OF THE CORONATION OF THE ICON OF OUR LADY OF CZĘSTOCHOWA
On the occasion of the 300 th anniversary of the coronation of the Icon of Our Lady of Częstochowa, Narodowy Bank Polski has issued a collector banknote of the face value of 20 zł.
The banknote was put into circulation on 21 August 2017.
The front side of the banknote depicts images of the crowns bestowed by Pope Clement XI, with which the Icon of Our Lady of Częstochowa was crowned.
The back side feature a drawing taken from the collection of the Vatican Library, which was made in 1717, presenting the festive coronation of the miraculous icon, which took place at Jasna Góra Shrine on 8 September 1717.
The banknote, which commemorates the 300th anniversary of the coronation of thee Icon of Our Lady of Częstochowa , is the first Polish collector banknote on which a special watermark was applied. It is a composition of a multitoned watermark with a gradual transition of tones from light to dark, and an electrotype light image – a filigree. The watermark on the banknote depicts the coat of arms of the Pauline Order.
It is also the first Polish banknote on which the image visible in UV light is multi-colour. This is the image of the 18th century drawing from the back side of the banknote representing the coronation of the miraculous icon. The effect was achieved by additive mixing of light issued by fluorescent inks coloured red, green and blue.