Reasons behind Apple’s heavy investments in GT Advanced Technologies (GTAT) sapphire substrates go beyond iPhone component demands, according to a TechCrunch report. Aside from home buttons and camera lens cover demands, the sapphire substrate’s crystalline properties is also a reason as to why Apple is extending its interest in this area.

Synthetic sapphire is superior to glass, even better than Corning’s Gorilla Glass material. Sapphire is colorless and since it’s grown from a single crystal to be optically transparent it appears similar to glass. Scoring a 9 on the Mohs scale, sapphire is extremely hard—meaning it has better scratch resistance. Sapphire is about four times greater than Gorilla glass, said Matthew Hall, Director of the Center for Advanced Ceramic Technology at the Kazuo Inamori School of Engineering at Alfred University.

Sapphire’s hardness, scratch resistance, and toughness (how it resists fracture once it starts the crack) comes at a price. “The density of Gorilla Glass is 2.54 g/cm3 while sapphire is 3.98 g/cm3,” said Hall. “Given equal-sized pieces, Gorilla Glass will always be lighter.” The report revealed sapphire substrates optical qualities and absorption properties is also similar to glass. Despite of Gorilla Glass brighter images than sapphire manufacturability has been a key behind Apple’s decision of ensuring its own supply.

Display glass manufacturing is still more scalable and energy-efficient than sapphire, and there is no immediate solution for sapphire to compete with glass on economies of scale, according to hall. There are still questions about the methods of producing large amounts of thin sapphire that is not cost-prohibitive.

In 2012 GTAT acquired Twin Creeks Technologies and obtained patents and Hyperion ion implanter. In a press release, the company noted the “Hyperion ion implanter has the potential to minimize, or in some cases eliminate, the need for wafering saws, which would significantly lower the cost of production.” GTAT has also been developing a method for making sapphire sheets thinner than human hair, which is then laminated on top of glass material to protect it. This is a more cost-effective solution than pure sapphire sheet, according to TechCrunch.

A Cantor Fitzgerald analyst Brian White noted that sapphire glass accounts for about 11 percent of GTAT sales this year, which is about US$ 28.9 million in revenue. By 2014, GTAT is expected to earn US$ 480 million to US$ 640 million from sapphire business alone.

Apple had filed a ‘sapphire laminates’ patent earlier that discusses a variety of ways to laminate sapphire sheets together with other sapphire sheets or with glass. This production method has much lower costs than conventional sapphire production methods. The technology could be used to laminate the assembly together as in iPhones. Apple is expected to be able to cut sapphire substrate costs considerably by implementing this method, and can even introduce this new technology into wearable devices. For further details please see link.