SHANGHAI, Apr. 26 (SMM) – Spot copper in Shanghai was quoted at a premium of RMB 170-250/mt over SHFE 1305 copper contract on Friday. Traded prices for standard-quality copper were between RMB 52,300-52,650/mt, and RMB 52,350-52,800/mt for high-quality copper. SHFE 1308 copper contract moved lower after a high opening. Spot copper supply decreased. Offers for standard-quality copper were firm due to tight supplies. Some middlemen entered the market in the morning, but later sold goods out. Downstream producers increased purchases for the upcoming Chinese May Day holiday.