GUEST: It has been in my family since, like, the early 1900s. Maybe even a little bit before. My father's great-great-aunt, so my great-great-great-aunt, they were wealthy. They had an import-export business of bananas. She loved to shop. So she was dear friends with, uh, Mrs. Statler of the hotel fame, and they would just go shopping all the time. Unfortunately, when she passed away in the early '70s-- I think it was 1970 or maybe '71-- my father wanted to buy it from the estate for $20,000, and his mom had said, "Don't buy it. "You can't wear that anywhere. It's an invitation to murder."

APPRAISER: (laughs)

GUEST: So my dad bought it anyway because he was that guy, and my mom wore it one time to a costume party.

APPRAISER: What was her costume?

GUEST: I think that she was, like, a flapper.

APPRAISER: Oh.

GUEST: With the dresses. And so she wore the choker...

APPRAISER: Mm-hmm.

GUEST: ...not as bracelets, and that was it.

APPRAISER: Well...

GUEST: And it's been away since then.

APPRAISER: Totally fitting that she wore it as a flapper, because it firmly dates to the mid-1920s.

GUEST: Yeah?

APPRAISER: I'd say about 1925. So this is a beautiful Art Deco platinum and diamond convertible necklace that converts into two bracelets. And jewelry from this period is a signifier of wealth, but it's still really versatile. It has multiple purposes. Obviously, you could wear it as a more discreet bracelet with the smaller diamond, or you could put it all together here and wear it as a choker, with the central stone being the prominent feature. So that central stone is five-and-a-half carats.

GUEST: Oh, my gosh!

APPRAISER: Yeah. There's about 15 carats in the rest of the two bracelets, and when they come together as a necklace.

GUEST: Yeah.

APPRAISER: And then there's another diamond in the back...

GUEST: It's, like, a smaller little round one.

APPRAISER: Exactly.

GUEST: Yeah.

APPRAISER: So the pattern repeats, again, in the back with, oh, about... It's about a carat and three-quarters. Altogether, it's about 23 carats of diamonds. In the early part of the 20th century, there was a huge influx of wealth, and at the same time, there was a huge influx of diamonds. There was a diamond that was discovered in the Cape Colony of South Africa around 1867, which really increased the diamond output in the world 20-fold. What had been sort of a rare thing was much more accessible. It would be controlled. But if you were an early-20th-century industrialist, socialite lady who loved to shop...

GUEST: (laughs) Shop, yes!

APPRAISER: ...you could go and get a wowza necklace like this. It was very, very in fashion. It's not signed, which is the only thing that would really add any more to its value. It is in a fitted box, which I believe to be original, that is also unsigned. So no real clues about exactly who made it. But I would put my money on the fact that it was probably made right here in New York. New York was a huge jewelry manufacturing hub at that time. The stones are certainly from that, those Cape mines that I mentioned. They're what the trade refers to as Cape Color, and that means they normally have some yellow tints. So you can see, especially in the larger stone, that it has flashes of some yellow in the L, M, N range for diamond grading. But it's very clean, it's very lively, and it's what we refer to as an old European-cut. And it has these sort of big, wide facets that really make it sparkle in low-light situations. So if you're here at a Gatsby-esque party, you know...

GUEST: Which is perfect for it.

APPRAISER: Perfect for where we are.

GUEST: We're ready, we're ready.

APPRAISER: It, you would see it from across the room. Conservatively, I would give it an auction estimate of $60,000 to $90,000.

GUEST: (gasping): Wow!

APPRAISER: And I would not be surprised by any means if it performed at the high end of that range.

GUEST: Oh, my goodness. Thank you.

APPRAISER: It is beautiful.

GUEST: Ooh! How fun!

APPRAISER: If this were a signed piece of jewelry, you could triple that number.