GUEST: This necklace belonged to my great-grandmother, and she lived from about 1864 to 1926, and I believe at the time they were quite wealthy. They came from northern New Jersey and they actually had a house there that is locally known as Kip's Castle, and I believe the county has just taken it over as a museum. I really don't know much about it. It's been passed down to me, and I think I've had it for about 35 years.

APPRAISER: You do have a hand-painted portrait of your great-grandmother, and in the portrait, your great-grandmother is wearing this particular necklace. The necklace is a wonderful piece from the early 1900s. I would date it most likely between 1900 and 1908.

GUEST: Oh, okay.

APPRAISER: What's remarkable is that not only is the front elegant, but the reverse is just as beautifully done. Every attention to detail was made. We look at all the individual little fret lines and the wire work that was done. Truly a remarkable piece. What we have in the center is a black opal.

GUEST: Black opal?

APPRAISER: Yes, most people are more familiar with the common white opals, but this makes it a much more expensive piece. Black opal is considerably more rare.

GUEST: Oh, okay.

APPRAISER: The green stones are Russian demantoid garnets. That is the most rare form of green garnet that exists. So this was a very expensive piece when it was made. From an auction standpoint, we can look at this from three different viewpoints. The first would be as a wonderful piece of historic jewelry, it would be $8,000 to $10,000.

GUEST: Oh, my word.

APPRAISER: Now, if we add in another element, which is the fact that this piece was made by Tiffany, it affects the value. A Tiffany piece would be priced at $15,000 to $20,000.

GUEST: Oh, my word, I just can't believe it!

APPRAISER: The general consensus is that we could take it a step further and assign this piece to Louis Comfort Tiffany, and he is known more for his stained glass, but he did also head up Tiffany Jewelers. And with his name attached, the auction estimate on a piece like this can go as high as $30,000 to $40,000.

GUEST: Oh! I can't believe this!

APPRAISER: Now, we have not found his initials on the reverse, so in order to achieve the highest value, we'd recommend that you contact the Tiffany archives. The archives can research the piece. They can date it correctly. They do this for a fee. The archives are based in New Jersey, and the last time I sent a piece there, they charged $1,000 to authenticate it. But when you're talking about a difference in price, it's a good investment.

GUEST: Yes, definitely.