* Oil starts week with more losses, gold bounces* Stocks lower after last week&aposs sharp swings* Investors await earnings; Tiffany&aposs slumps(Updates to close of U.S. trading)By Ryan VlastelicaNEW YORK, Jan 12 (Reuters) - Most stock markets around the world fell on Monday as oil prices showed no sign of breaking their prolonged downward spiral, prompting further losses in beleaguered energy sh