Take a big ugly looking washboard mussel from the fresh water of Kentucky Lake in Camden, TN, cross your fingers, open it up and - whooee - there it is, a big beautiful miracle of nature (with man's help): a lustrous pearl the size of a pea!

The miracle is the work of pearl farmers Don Nerren and Bob Keast at the Tennessee River Pearl Farm off Interstate 40 in West Tennessee. The day we visited the farm, Don's son John, looking more like some creature from the black lagoon, popped up through the river's surface in full wetsuit-headlamp-diving mask and pump-fed breathing apparatus. In his hand was a heavy net bag filled with big mollusks, mussels he'd collected from the river bottom during a multi-hour hunt.

Tossing the bag and a belt-full of weights into the little fishing boat with its air pump now shut down, John hoisted himself onto the boat's gunnel, grabbed a large mussel and - with all the skill and finesse of a New Orleans oyster shucker - opened it with a big knife pulled from an ankle sheath. With a big grin, he showed us the mussel's meaty interior - and an amazing five pearls growing inside.

Usually there's maybe a little pear-colored something inside the mussels harvested from the riverbed. The real reason for the dangerous dive is the mussels' shell. Sanded and polished it becomes lustrous mother-of-pearl, shaved thin for inlays in knives, lighters, furniture and artworks. Or cut into small shapes, including round balls the size of BBs or little marbles, to be implanted in living mussels to form the nucleus of a pearl.

The mussel, irritated by the implant, secrets layers of nacre around it and within a couple of years it has created a beautiful pearl shaped like the implanted irritant - spherical, square, triangular, oblong.

Here's the curious part: the diver sells his harvested mussels to an exporter who ships them to pearl farms around the world to be processed into mother-of-pearl slivers, jewelry and implants. The famous Mikimoto strand of Japanese pearls you paid a little fortune for may very well have been started by a lovely ball of Tennessee mussel shell. In the cultured pearl business, what goes around comes around.

At the Tennessee River Pearl Farm (the only one in America), Nerren and his staff buy selected live mussels from divers, tag them with diver's name and date, then secure them in special baskets 24 inches below the surface to acclimate for a year in the food- and oxygen-rich river water flowing past them before "nucleated" with up to four mother-of-pearl irritants and returned to hang in the seven-acre "farm" waters for up to four years. Ninety percent will produce pearls.

Tennessee declared them their state gem in 1979 - and Kentucky joined suit in 1999. Visitors can tour the farm's museum, see an interesting video and demonstration of harvesting - but not the lab-controlled implanting process. That's a secret that's been carefully protected by its Japanese cultivators, but learned through years of trial and error by entrepreneur John Latendresse and his Japanese wife who had their first successful harvest in 1986. His original farm is now adjacent to Birdsong Resort and Marina. For a fascinating glimpse into the world of pearl cultivation, dive down to www.TennesseeRiverPearls.com or call 800-225-7469 to book a tour, a room, or both.