Well, we've since learned that the pin was a custom-made creation by the Italian-based jewelry company Garavelli. According to our friends at the jewelry house (they do a lot of beautiful diamond pave hoops, FYI), the brooch was purchased from her long-time Chicago jeweler by President Obama as a gift for their anniversary this past October.
And there you have it.
Below, some more Garavelli creations, from our market appointment with them in Basel.
Related: Five minutes with Mrs. Obama's hairstylist