On the day of the Inauguration, there was much intrigue about the necklace - or was it a pin? - worn at the collar of Mrs. O's Isabel Toledo lemongrass dress. Questions would be answered soon enough.

The mystery accessory proved to be a Victorian sash pin, acquired through the Carole Tanenbaum Vintage Collection. The discovery of Carole Tanenbaum's collection, a finely curated, hand-picked selection of costume jewelry has opened up a new world for us.

We now often visit the collection's site to admire the distinctive pieces, or to read updates on Carole's blog (the Carole Tanenbaum Vintage Collection provided jewelry worn in Grey Gardens, which premieres this evening on HBO). The collection has also revealed a few more secrets about Mrs. O's enviable brooch collection.

On a campaign stop in Pittsburgh last October, Mrs. O wore an orange flower pin at the shoulder of her Abstract rose print J.Crew dress. We recognized a similar pin on Carole's site - a rare Hattie Carnegie silk flower pin from the 1960s - and later confirmed that indeed Mrs. O's pin was Hattie Carnegie as well. We were unfamiliar with the designer at the time, but eager to learn more.

In 1904, Henrietta Kanengeiser emigrated to the US from Austria-Hungary at the age of 18. After changing her name to Hattie Carnegie in 1909, she opened a millinery shop on E. 10th Street in New York City called Carnegie - Ladies Hatter. In 1923, the flagship Hattie Carnegie boutique opened at 42 East 49th Street. 

En route, Hattie Carnegie had begun manufacturing a high quality costume jewelry line in 1918, which continued to be sold after her death in 1959 and well into the 1980s. Carole Tanenbaum's collection offers rare Hattie Carnegie pieces of the highest quality and finest condition for the serious costume jewelry collector. For those who don't mind a few scratches or missing stones, and pieces that likely aren't as rare, eBay also has a range of Hattie Carnegie pieces up for auction.

A quick search led us to the following: #1 Bee brooch, #2 Turquoise flower pin, #3 Blue flower pin. The pear pin shown above is a Hattie Carnegie pin (stamped "Hattie Carnegie" on the back), acquired a few weeks ago. It has signs of wear - the paint is chipped in a few places, the closure a bit bent - but we will treasure it, and the hidden connection to Mrs. O, none the less.