Bohemian Brooch Intaglio on Mother Of Pearl

Sweet little brooch that took a bit of time to find out the correct information on where and when this was made.
Examples are shown in Jargstorf's 'Baubles, Buttons and Beads: The Heritage of Bohemia and described as a early 20th century crystal cabochon with molded and painted intaglio on the back set on a mother of pearl plate.
I originally thought this was Goofus Glass as that is what I was seeing them described as, you also see them described as Essex Crystals, both are incorrect though.
Thanks to Cheryl for providing me with the correct information.