Diamonds emerge from myth, sparkling gems endowed with mystery, timelessness and beauty.

Well, sometimes. Other times the diamonds will come from a factory in an industrial park. In Gresham.

British diamond specialist De Beers Group said this week it will spend $94 million over four years to build a 60,000-square-foot Gresham factory for manufacturing synthetic diamonds. Construction will start this summer and the facility will eventually employ about 60, according to economic development officials.

The synthetic gems will sell for $200 for a quarter-carat stone and $800 for a one-carat version, according to the company. That's about one-tenth of what its conventional diamonds cost and cheaper than prior synthetics from other companies.

De Beers is the latest in a series of companies to pursue the synthetic market. It had previously disdained the synthetics, insisting natural diamonds are superior. Companies are hedging, though, as synthetic quality improves with similar physical characteristics as natural diamonds and as competition heats up.

News of De Beers' reversal created a bit of a stir in the diamond industry this week, and the company dismissed the distinctiveness of its new products. De Beers announced it would not grade its synthetic, lab-grown diamonds because "we don't think they deserve to be graded."

"Lab grown are not special, they're not real, they're not unique. You can make exactly the same one again and again," Bruce Cleaver, De Beers' chief executive, told Bloomberg in an interview Tuesday.

De Beers had, though, already been making synthetics for industrial customers. It described the expansion into fashion-oriented synthetics as a natural extension of its business and said the synthetics are "for lighter moods and lighter moments," suggesting the synthetics might be more appropriate for occasions like a trip to the beach or a high school prom.

Conventional diamonds are typically more than 1 billion years old, formed deep inside the Earth under extreme pressure and high temperatures, ultimately carried toward the surface by volcanic eruptions.

De Beers said it makes synthetics by placing a "seed" into a plasma reactor, heating it to over 6,000 degrees, then pummeling it with carbon atoms. The newly manufactured diamond is ready for cutting after 400 to 500 hours, according to the company.

De Beers said the manufacturing process is extremely energy intensive and so the Northwest's relatively low electricity costs were one factor in choosing Gresham for the new factory.

"Given the pressure required to create lab-grown diamonds, it's akin to the Eiffel Tower being stacked on a can of Coke," Steve Coe, head of De Beers' synthetic jewelry subsidiary, told The New York Times. "If you look at the detailed numbers, the energy consumption levels between natural and man-made diamonds are in the same ballpark."

The Gresham plant will eventually have capacity to produce more than 500,000 rough carats of synthetic gems per year, according to De Beers.

To distinguish the synthetics from natural diamonds, De Beers will market them under the Lightbox Jewelry brand and mark them with a logo too small to see with the naked eye but visible to jewelers with magnifying glasses.

De Beers' factory will be in the Gresham Vista Business Park, adjacent to the ON Semiconductor plant at Northeast Glisan Street and Northeast 223rd Avenue. The Port of Portland bought the property in 2011 to encourage industrial development.

The factory is in an enterprise zone, meaning at least some of De Beers' investment will be exempt from the local property taxes other businesses pay. The company has just submitted its enterprise zone application, according to the city, which said it has yet to calculate the value of the incentives.

-- Mike Rogoway | twitter: @rogoway | 503-294-7699