UPDATE 1 — Vietnam's Masan High — Tech to sell stake to Elmet and sign tungsten supply deal
(Adds details of company valuation and supply deal) HANOI, Sept 24 (Reuters) — Vietnamese tungsten producer Masan High-Tech Materials Corp said on Thursday it will sell a 4.99% stake to US-based tungsten products supplier Elmet Group, in a deal that values the Vietnamese company at about $2.5 billion. Masan High-Tech a