SHANGHAI, Dec. 6 (SMM) –Shanghai spot copper offers were quoted between discounts of negative RMB 50/mt and premiums of positive RMB 80/mt today. Traded prices for standard-quality copper were between RMB 57,900-58,000/mt, and RMB 57,950-58,120/mt for high-quality copper. SHFE copper prices fluctuated after a low open, but an increase in spot copper supply caused copper premiums to fall all the way, with imported standard-quality copper traded at discounts. Downstream producers were seen to make purchases at prices below RMB 58,000/mt, and speculators also increased purchases at low copper premium levels, leading to an improvement in market transactions.