While the world’s biggest diamond miner surprised the market by cutting prices this week, a slew of filings from its smaller rivals show the move was inevitable. While De Beers is a price maker in the supply of rough diamonds, dictating what its customers pay, most other miners are price takers. Gem Diamonds Ltd. and Lucara Diamond Corp. -- both known for digging up the most-expensive stones -- and Mountain Province Diamonds Inc. all reported lower prices this week. Much of the industry’s current problems have focused on tumbling prices for cheaper, smaller goods, the sort of diamonds that end up in a Walmart ring, ... (full story)