(TheDrinksBusiness) - A string of sales of premium vineyard properties across California this year is set to make 2012 the most successful since the previous peak of 2007. Sales of Californian wineries and vineyards are due to reach US$800 million by the end of the year, according to San Francisco-based consultants Demeter Group, reports Bloomberg. Buoyant interest in California has seen premium purchases this year such as PlumpJack Winery buying 50 acres in the Stag’s Leap district of the Napa Valley.