Rubicon Technology, Inc. (NASDAQ:RBCN), a leading provider of sapphire substrates and products to the LED, semiconductor, and optical markets, today announced that Warren S. Stewart III has joined the Company as Senior Vice President of Sales and Marketing, effective immediately. Mr. Stewart was formerly Vice President, Sales, at Cree, Inc., in Durham, North Carolina. He will provide leadership to Rubicon’s global sales and marketing team, reporting to Raja M. Parvez, President and Chief Executive Officer.