GUEST: My father was in Cornish, Maine, in a resale shop.

I was just about to graduate from college about 20 years, 20-plus years ago.

My father ended up paying about $60 for this piece and, uh, gave it to me for graduation.

APPRAISER: It's a poster for an exhibition that Robert Indiana had of his works at the Stable Gallery in New York in 1966.

So this is, in fact, a poster from 1966, authentically from that era.

GUEST: Really?

Wow.

(chuckles) APPRAISER: It was his third exhibition at the Stable Gallery.

Historically, that's been referred to as "the LOVE Exhibition," and it was referred to as "the LOVE Exhibition" because it was the first time that he publicly displayed his LOVE paintings.

GUEST: Wow.

APPRAISER: And these LOVE" paintings have really become such an iconic part of the American cultural landscape.

They've been on postage stamps, they're statues, they exist in paintings, all different sizes and colors.

The artist first came up with the idea in 1964, and he sent a holiday card to his friends with the "LOVE" logo on it.

The next year, in 1965, he designed a Christmas card for the Museum of Modern Art in New York...

GUEST: Mm-hmm.

APPRAISER: ...which they still claim to this day was their best-selling Christmas card ever.

GUEST: Wow.

APPRAISER: And then the following year, when he had his third exhibition at the Stable Gallery, he designed this poster.

So, I'm a poster geek, and I say that very proudly.

GUEST: (chuckles) APPRAISER: And for me, this is the first poster representation of this iconic American artistic form-- the first time that "LOVE," the Robert Indiana "LOVE," appeared in a poster.

The colors are still really bright.

And the predominant colors, which fit in so beautifully here...

GUEST: (chuckling): Yes.

APPRAISER: Right?

Are the green, the blue, and the red.

And a lot of people posit that these colors represented for the artist Phillips 66, the petroleum company-- his father worked for the company.

GUEST: Oh.

APPRAISER: And their neon sign above Indianapolis, where he lived, had these colors.

So they say that that was perhaps what influenced him in this first series to use the red, green, and blue as the predominant colors.

GUEST: That's amazing.

APPRAISER: A lot of Robert Indiana's posters were mass-produced.

GUEST: Mm-hmm.

APPRAISER: They were done for exhibitions at larger museums.

So they have lesser value because there's more of them.

In this case, the supply is not that big.

The Stable Gallery was not a particularly big gallery.

We don't actually know how many were printed.

GUEST: Mm-hmm.

APPRAISER: But we know that not that many have survived.

GUEST: Wow.

APPRAISER: It's done, uh, via a process of screen printing, which is also a, a process by which not that many could ultimately be made-- there were probably a few hundred or maybe even a thousand, that would be my, my guesstimate.

When these come up for auction nowadays, you can expect them to sell for between $2,500 and $3,500.

GUEST: Fabulous.

APPRAISER: Every once in a while, you see one of these posters that's also hand-signed by him.

And in that case, the price would be almost doubled.