(IDEX Online) - GIA has laid off around a fifth of the workforce at its HQ in Carlsbad, California, amid a significant drop in the number of diamonds submitted for grading.In total 151 workers will leave their positions at Gemological Institute of America (GIA) later this month. Most are laboratory workers, a few hold corporate positions. "We receive stones generally from either the companies that cut and polish them or sometimes from the companies that make the actual jewelry pieces, or sometimes from retailers and also from consumers," said GIA director of communications Stephen Morisseau. "And there's just been a general downturn in those submissions because of the general economic conditions affecting the global gem and jewelry trade."The San Diego Union-Tribune, which first reported the story, said around 600 workers would remain at the 35-acre Carlsbad campus. GIA, a nonprofit founded in 1931, has a total of 3,500 employees worldwide, with laboratories in New York, Hong Kong Tokyo and other major cities. Pic of the Carlsbad HQ, courtesy GIA.