While the cost of copper is going up for American businesses and consumers, the rest of the world is scratching its head while it enjoys a considerable discount on the price of copper.

Prices for the metal hit a record high after the president suggested a higher rate than many analysts were expecting.

Donald Trump's mooted 50% tariff on copper imports into America has sharply exacerbated what was already a dislocation between New York and London prices for the metal. The chart shows that since Trump's inauguration traders have been placing a greater premium on the COMEX contract,