Worried that demand is stagnating and a new generation is turning its back on diamonds, the industry is promoting a wide variety of initiatives to appeal to consumers. In addition to the generic ad campaign De Beers announced for holiday 2015, the trade is pursuing the following campaigns: •    Signet and Forevermark joined forces over the holiday to promote the two-stone ring, with an ongoing campaign that calls to mind De Beers’ past “beacons.”  •    The Diamond Producers Association, the newly formed group of diamond miners, has enlisted New York City agency Mother for a marketing campaign and has hired De Beers and World Gold Council veteran Sally Morrison as its marketing director. •    The World Diamond Council is looking for a public relations firm to handle “reputation management issues,” a PR newslette