Gold firmed on Tuesday as fears of further ratings downgrades in Europe spurred buying from speculators, but demand from jewellers slowed to a trickle in Asia, with most orders already filled before the year-end holidays. Spot gold added $2.90 an ounce to $1,387.80 an ounce by 0706 GMT in thin trade, which means that prices are prone to sharp movements. Gold was well below a historical high of around $1,430 hit earlier this month.