Four years ago at the height of smartwatch hype, it was the most desirable mineral in the world. The tech superpowers jostled to obtain supplies of the material, just as the superpowers jostled to secure their nitrate supplies* ahead of the First World War.
Sapphire would become the main ingredient in smartphone displays – as well as the smartwatches everyone would soon be wearing.** Sapphire displays were four times tougher than glass and exceptionally difficult to scratch. Panic broke out when Apple was said to have secured the world's supply of the sapphire for three years.
However, larger sapphire displays were expensive and difficult to manufacture. Apple supplier GT Technologies, which had built a factory in Mesa, Arizona, went bust. The iPhone 6 appeared without a sapphire display, and while it continued to appear on small parts – such as lens coverings and watches – only luxury brands used it for smartphone displays.
The problem with scratch-proof materials – which score higher up the Mohs scale – is that they shatter more easily. Corning Inc devotes about a billion dollars a year to R&D and this this week announced its sixth-generation Gorilla Glass. Corning claims it should be able to withstand 15 drops from one metre onto a hard surface, twice the resistance of Gorilla Glass 5.
Only Motorola has gone truly shatterproof, eschewing glass for plastic with its Force phones. If you're a serial phone-dropper, the year-old Z Force 2 is still the one for you. The plastic is so scratch prone you'll need a screen protector, we found, but after that it's a brute.
With many more phones now fitting glass backs that should mean a vigorous market for materials suppliers.
Ultimately sapphire didn't become the dominant mineral in displays because it was some two to three times as expensive to manufacture, and some 67 per cent heavier.
The good-enough gorilla won.®
* Whoever had the most nitrates would win any large war, strategists believed. The other side would run out of explosives. Synthetic nitrate production only achieved scale after the war's end.