Financial uncertainty around the world following the presidential result has seen demand for gold - seen as a safe haven investment - rocket.
Rob Halliday-Stein, from wholesaler BullionByPost in Birmingham, said: "It's gone nuts, absolutely bonkers."
Gold has been trading above £1,050 an ounce, above a six-month low of £821.
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Mr Halliday-Stein, who set up his firm in the city in 2008, said: "Trump equals more uncertainty, and normally that means it's a good time to get into gold.
"This is looking like it will be our best day of trading in eight years.
"We've done a good few million already, and it's getting towards £10m."
Republican Donald Trump beat Democrat Hillary Clinton to the 270 electoral votes required to become the 45th US president.
The result caused gold to initially jump 5% although it has now fallen back to more modest gains.
Donald Trump's election win has blessed a gold dealer with sales of almost £10m - the best day's trading in eight years.