Gold futures traded at US$1835.80 an ounce, the highest level since mid-June, and rose as high as $1837.50/oz.
"Gold is trading firmer following the FOMC meeting; however, the move still seems underwhelming given the latest move in real rates and the US dollar," UBS said.
"Market participants have been wondering about gold's relationship with real rates, which seems to have broken down since the June FOMC meeting. The decline in real rates to fresh lows has not been sufficient to encourage a material rebuild of positions as market participants continue to contemplate the likely timing of a Fed taper.
"Although real rates are even lower now than they were last August, when gold prices made new highs, the backdrop is different and so are investor outlooks."
Silver jumped 3.6% to a two-week high of US$25.78/oz.
Iron ore prices are down just under 6% this week, while floods in China have created supply chain issues and bolstered the price of some commodities, with aluminium now at a three-year high.
Among the base metals, nickel rose 1.5% to a new seven-year high of $19,833 per tonne.
Copper hit a six-week high of $9799/t.