“We had some clients call and once we step them through the numbers, they sober up,” he said. “The valuation is 100 times earnings in a stock market that is trading at 12.”

“At the end of the day, if you have a small amount of money that you are in a position to lose a chunk of it and you want to speculate on Facebook, go ahead,” he added. “But don’t use money that you really need to save to do it. I would put it in Microsoft, which is dirt cheap right now.”…

But the sheer size of Facebook’s valuation means that it will have to become the world’s first $700 billion company if it is to replicate the gain in Google’s stock.

“At these valuations, investors really need to set aside emotion…and invest with their heads,” said Edward Reinhart, managing partner at Capital Advisors Wealth Management, who owns Facebook shares bought on private markets two years ago.