As many of the world's developed markets move toward saturation with smartphone penetration, emerging markets have become increasingly critical in driving growth for handset makers like Apple (AAPL 0.53%) and Samsung. The crown jewel of emerging markets is China, the world's largest smartphone market. And it's exactly that size that makes it one of the most closely watched markets by analysts and investors alike. In the video below, Fool contributor Andrew Tonner tells investors about one significant trend in this major market.