How should investors gauge these red-hot stocks with seemingly unbridled share prices? Cramer said he's always willing to pay a multiple that's up to twice a company's growth rate. So for a company growing its earnings at 20% a year, Cramer said he's willing to pay up to 40 times earnings for it. Investors must pay close attention to which way a growth company's earnings are headed, however. These high fliers can seem to soar endlessly if earnings are accelerating and analysts are scrambling to raise their estimates to fit that growth. But as soon as earnings slip and those estimates are not met, the downward gravitational pull can cause shares to take a pounding. This was certainly the case with Apple throughout much of 2012 and 2013, said Cramer, and the same can be said for Chipotle, Blackberry ( BBRY), Nokia ( NOK) and Chipotle. When you see multiples compress, be prepared for a bumpy ride, Cramer concluded.