GUEST: My family's always called it the Marie Antoinette mirror.

Because we've been told that it was Marie Antoinette's mirror.

My mother must have bought it, I think in San Francisco, in the 1950s, perhaps, and I know that it's very fragile and it's got to be old, because it's got all these beautiful pieces going on.

I don't know what the stones are.

I'd like to know about that.

APPRAISER: Okay.

Now, what really grabbed me when it came through the door is that it's made of porphyry.

And porphyry is a red marble that is mined in Egypt.

Eventually, that stone gets mined out completely.

There is very little or no Egyptian porphyry left.

That having been said, other mines of porphyry have been found around the world.

But you see how elaborate this is.

It has porphyry columns, it has porphyry plaques, it has a porphyry base.

And then we begin to look at the, at the bronze castings.

And if we look at the lions that are here, those are exceptionally good quality, because after it gets taken out of the foundry, a lot of this is worked by hand.

So we've got two positive things going for it.

And we look at the open work here, up in the cresting, and that's very nice, too.

And on the back here, you have the initials "A.R."

and the date in Roman numerals, 1787.

Now, what does "A.R."

stand for?

It stands for "Antoinette Regina," which is Queen Antoinette.

As we delve into the mirror a little bit more, I sort of turn my attention to these pieces of crystal here.

And I'm thinking that if this piece is truly 1780, 1787, the quality in these pieces of glass would be commensurate with the enormous cost in putting the piece of porphyry together.

And then you think about when this could have been made again.

And it leads you to the 19th century, and probably the era just around 1875, 1885, which is about a hundred years after Marie Antoinette would have owned it.

GUEST: Right.

APPRAISER: Unfortunately, what we have here and we've got the nice plaque down here the writing on the back is inconsistent with what you would have found if she had actually owned the piece.

And truthfully, what they've done is they've taken an item that was legitimately very good and now rendered doubt on it.

This is almost certainly French, and this is not a fake.

This is a legitimately good piece from the latter half of the 1800s that someone has added information to, that is incorrect.

What we've done is we've taken an object which, at auction, would probably bring around $25,000 to $30,000 GUEST: Okay.

APPRAISER: and because we put on the back information that misleads you, you lose value.

GUEST: Okay.

APPRAISER: And so now, at auction, it's about $18,000 to $20,000, but it's still a wonderful piece, and I love it.

So GUEST: It is a great piece.

It's a fun piece.

Thank you, Stuart.

APPRAISER: If this was owned by Marie Antoinette, its value would be in excess of $500,000.