TeslaCEO Elon Musk responded to Amazon.Com Inc on Monday with a silver emoji.A tweet from founder Jeff Bezos reminds him that the wealth gap between the two is widening.

With the recent rise in Tesla, Inc. 's share price, Musk once again surpassed Bezos to become the world's richest man, according to the Forbes real-time rich list at the end of last month. Musk wrote to Forbes at the time, "I'm going to give a huge statue of the number 2 to Jeffrey B. and a silver medal."

On Friday, a deal between Musk's space exploration technology company (SpaceX) and investors valued the company at more than $100 billion, more than four times that of Bezos's Blue Origin.

This increased Musk's worth by about $9 billion. Musk is currently worth $222 billion, $31.2 billion more than Bezos's $190.8 billion, according to the Bloomberg Billionaires Index.