(IDEX Online) - Artisanal diamond miners in Liberia have received basic training in grading and valuing gems.The move, by the Japanese NGO Diamonds for Peace, is designed to help them avoid exploitation, and to negotiate a fair price for their stones.A trainer from the UK spent two days teaching a group of 25 miners from communities in the northern counties of Bomi and Gbarpolu. Many participants admitted they had no knowledge at all about the diamonds they were mining before they learned about the 4Cs and basic valuation techniques. They were all given a loupe, scales and other items.Liberia has long been at the center of blood diamonds allegations. The country has a long history of alluvial diamond production - 14 million carats in the last 50 years - but has very little in the way of large-scale diamond production.Generic pic of artisanal diamond miners.