Unfortunately, your brooch is not D&E/Juliana. All Juliana pin backs have pin stops. Yours does not appear to have one. This is also a great resource for locating D&E pieces: http://www.isitjulianajewelry.com/
I think the other members told me it is a portrait of Aphrodite attributed to an artist from the 1800s, but someone else identified it as a modern painting. And I don't remember, sorry!