Top stone-cutters and jewelers from around the world will offer pieces for sale at prices ranging from $2-$20,000, and collections of some of the most prized gems and minerals in North America will be displayed by invited museums and individual collectors and clubs.

Looking and learning at the show is free with admission to the museum today, Saturday and Sunday, and stones and jewels will be on sale in a broad range of prices.

"You can go to booths that have beautiful expensive gems and jewelry, but at the same time you can go to some rockhound's booth and get some inexpensive moqui marbles," says Tey Stiteler, communications manager of the Carnegie Museum of Art.

Finished jewelry will be on display, along with stones that are in their raw, "just-chipped-out-of-the-cave state," Stiteler says.

Gems don't come out of the earth looking destined for the jewelry store window.

"Every gemstone starts as a rough mineral that's usually found in the ground or mined out of the ground, and then they have to be fashioned so that when light enters the stone or reflects off the surface, you see the brilliance and shine and sparkle that each piece of rough potentially has," says Don Laufer, a graduate gemologist of the Gemological Institute of the America, who will be demonstrating gem cutting, answering questions about gem stone evaluation and identification, and selling loose gem stones and jewelry he's made.

Finding rich colors in the rough is a passion that began as Laufer's childhood hobby. In 1968, the pastor of the church he belonged to showed him how to cut the stones Laufer had been collecting for four or five years.

"The colors got me into collecting minerals at first," Laufer says. "Then I decided I would like to be able to take a rough rock that doesn't look like much at first and take it and polish it and shape it into something beautiful."

His Headwaters Lapidary in Canonsburg lets him do this with purple amethysts, red and green alexandrite, sparkling diamonds, black onyx and agate -- his favorite gemstone for its unlimited and never-ending colors and patterns.

Visitors to the show who purchase loose stones from vendors such as Laufer, or who have treasures of their own that they'd like to turn into a necklace, earrings, pendant, bracelet or ring, can stop by the Fowler's Wirewrapping booth. Jim Fowler has been making jewelry with stones and gold and silver wire spirals and scrolls for 36 years.

"It's more like a wire artist; I'm beyond the point of being just a wire guy," says the 72-year-old inductee for metalcraft of the National Rockhound & Lapidary Hall of Fame.

Fowler will craft customized jewelry at the show in 15 minutes to an hour, and he also will be bringing 18 cases of his own wire work, in addition to some that his wife has created.

"We set anything from minerals to faceted stones, cabochons, diamonds -- whatever they want," says Fowler, who lives in Marlboro, N.H.

He's fashioned a ring for a man with a size 23 1/2 finger and has also been presented with 400-carat stone to place on a size 7 ring.

"That's like putting a pound of butter on your finger," Fowler says. "At least let me make it for two fingers, or you're not going to hold it up."

When working as a union welder and pipe fitter, Fowler would find himself needing a way to fill his time after he completed his work. He began fashioning stainless steel nuts into rings and filing double hearts into the top. Later, when he saw some wirework at a rock show, he said to himself, "I think I could go home and do that."

By talking with and watching demonstrations by the 37 vendors at the show, visitors can leave the Natural History Museum with a heightened appreciation and understanding for the study of the rocks, stones and gems they see at the show.

The history museum's Hillman Hall of Minerals & Gems exhibit hall will be closed during the gem and mineral show. The gallery is undergoing an expansion and will reopen in early 2007 with a complete remodel that will feature a changing exhibit of gems, birthstones and jewelry.

Young gemologists who visit the gem and mineral show can pan for gems at a working sluice in the Discover Room of the museum, take home some of the specimens they find, learn about pearls and birthstones, and see a miniature replica of a working mine.

"When you think about life on earth, and you think of moving through time, the geology is an extremely important part of history of life on earth. Related to that is the study of gems and minerals and rocks," Julian says.