Apple and GT

Industrial sapphire might be your next smartphone display

GT Advanced Technologies tries to scratch a sapphire smartphone cover with a sharp pebble (see video)

BARCELONA, Spain -- Sapphire could someday be used in some smartphone displays instead of the toughened Gorilla Glass popular today.

In this case, however, it would be man-made sapphire, not the rare blue gemstone that is taken from the ground and used in jewelry.

GT Advanced Technologies hopes that a new furnace it makes to produce industrial sapphire from the plentiful raw material corundum will help lower its cost enough to persuade makers of smartphones and ruggedized devices to switch to sapphire instead of glass. One furnace can cost between $300,000 and $400,000.

Today, smartphone glass costs about $1 per diagonal inch in a smartphone, compared to $3 to $4 per inch for sapphire, said GT's Jeff Nestel-Patt, director of marketing communications.

That cost could drop dramatically in the next two years, as GT's Advanced Sapphire Furnace is used to produce manufactured sapphire, he said. The furnace heats to 2200 degrees Celsius, helping to create the huge sapphire boule after 16 days of curing. The boule can then be sliced into thin display material.

Sapphire is already used in smartphone camera lenses because it is so tough, Nestel-Patt said in an interview at Mobile World Congress (MWC) here. In a demonstration, he tried to scratch a thin slice of sapphire mounted atop an iPhone 5 display with a sharp piece of concrete. After several seconds of scraping, tapping and even pounding, the concrete actually flaked off into tiny particles since the sapphire cover was actually harder.

Sapphire is the second-hardest material in the world behind diamond, and is harder than glass. On the Mohs mineral hardness scale, diamond gets a 10, sapphire a 9 and glass (made from quartz) a 7.

Nestel-Patt also showed how his concrete rock left a pretty significant scratch on a separate display made of toughened glass. The problem with too many scratches on a smartphone display is that they can weaken the display, eventually breaking it up entirely when dropped.

Sapphire also offers optical purity and is used to produce chips used in LED lights, GT officials said.

GT is just starting its campaign to promote the furnace, Nestel-Patt said. "The cost has come down to a point that we feel there's a broader opportunity to take sapphire to new market opportunities for device covers and touchscreens," he said.

GT Advanced Technologies thinks that sapphire glass could prolong the life of cell phones and other devices and protect them from rough treatment. Follow reporter Nick Barber on Twitter @nickjb

See more Mobile World Congress coverage from our team in Barcelona.

Matt Hamblen covers mobile and wireless, smartphones and other handhelds, and wireless networking for Computerworld. Follow Matt on Twitter at  @matthamblen or subscribe to Matt's RSS feed. His email address is

See more by Matt Hamblen on

Copyright © 2013 IDG Communications, Inc.

7 inconvenient truths about the hybrid work trend
Shop Tech Products at Amazon