Global oil prices tumbled below $90 per barrel after US President Trump announced "good talks" with Iran, raising hopes for a diplomatic breakthrough.

The cost of benchmark Brent crude dropped 8% to 87.55 US dollars a barrel at one stage in ongoing heightened volatility in oil and gas markets.

Brent crude fell 7.6% below $90 as US-Iran ceasefire hopes boosted equity futures. Here's what the oil price drop means for crypto investors.