* Exceeds average forecast by 21 percent
* Shares surge after hours
LOS ANGELES, May 5 (Reuters) - Rubicon Technology Inc (RBCN.O), which makes sapphire substrates for the light-emitting diode (LED) market, reported a quarterly profit that blew past analysts' estimates.
Net income was $19.1 million, or 80 cents per share, topping Wall Street analysts' average estimate of 66 cents a share, according to Thomson Reuters I/B/E/S. In the same period a year ago, Rubicon earned $1.6 million, or 7 cents per share, a year ago.
Revenue more than doubled to $38 million.
Shares in the company leapt 6.5 percent to $29.50 in extended trading from a regular-session close of $27.70. (Reporting by Nichola Groom; Editing by Phil Berlowitz)