International diamond producers on Friday unveiled a new marketing slogan "Real is Rare" to reach out to a younger generation of buyers, although major producer De Beers says diamonds will always be forever.

For well over half a century, diamonds have been marketed under the De Beers slogan A Diamond is Forever. But last year the Diamond Producers' Association (DPA), which groups producers such as De Beers, part of Anglo American, and Rio Tinto , was set up to spur demand.

It is looking to the millennial generation and the U.S. market, which accounts for about 45 percent of diamond demand, to drive a recovery.

At a jeweller fair in Las Vegas on Friday, the association said its new slogan was the result of six months of development, including in-depth research into millennial consumers.

"For many millennial, diamonds have come to represent traditional rituals or bling and status signifiers," the DPA said in a statement. "The opportunity exists for diamonds to represent the rare, precious and real connections that millennials crave."

Challenges for the diamond industry have included competition from synthetic diamonds, as well as uncertain demand from customers in the millennial generation, aged roughly 18 to 34.

Analysts and marketing experts said change can stimulate demand.

"Whilst consistency in image and communications is a good quality for a brand, we do see that refreshing the message and innovating are strong drivers of financial growth," Peter Walshe, a global strategy director at international market research firm Millward Brown, said.

De Beers says its A Diamond is Forever slogan, which dates from 1947, still resonates strongly and it will continue to use it.