One of the Top 10 World Class and Most Expensive Mobile Phones-- Sony Ericsson’s Black Diamond. Jaren Goh created this stylish concept for Sony. It features mirror detailing, polycarbonate mirror and an organic LED technology. Of course, when it comes to Sony, nobody can challenge the screen results. It is decorated with two diamonds, one on the navigation buttons and the other in the back of the phone. The price of this phone is $300,000.