Spot gold trades from roughly 22:00 UTC Sunday to 21:00 UTC Friday with a daily rollover break near 21:00 to 22:00 UTC. The Asian session ranges, the London open expands the range, and the London and New York overlap from 13:00 to 17:00 UTC carries the deepest liquidity.
The two most expensive windows are the 21:00 UTC rollover, when gold spreads widen sharply, and the 13:30 UTC US data release covering CPI, PPI, retail sales and Non-Farm Payrolls.