Apple CEO Tim Cook described the company ’ s eagerly anticipated watch as ‘ the most personal device we ’ ve ever created ’ . And it may be the California-based firm ’ s most durable too . A sapphire glass screen used in the device has remained scratch-free after being subjected to being rubbed with sandpaper , keyed and even hit with a hammer . Scroll down for video . A sapphire glass screen used in the device has remained unscratched after being subjected to being rubbed against a stone wall ( pictured ) and with sandpaper , keyed and even hit with a hammer . The test was carried out by Cardiff-based iPhone repairs specialist iPhoneFixed.co.uk , which used a sapphire screen from a 38mm Apple Watch for its experiment . Two out of the three models of Apple Watches , which are available to pre-order from today , have sapphire glass screens . Two out of the three models of Apple Watches , which are available to pre-order from today , have sapphire glass screens . The only one that does n't is the Sport model ( pictured above ) The glass is made from synthetic sapphire , which is created by applying heat and pressure to aluminium oxide powder , before being processed to remove impurities . Here , it withstands being scratched by sandpaper . Synthetic sapphire is a hard , transparent material made of crystallising aluminium oxide , produced at high temperatures and pressures . As the material is heated , it forms disks that can be sliced using diamond-coated saws . These round disks are ground into shape , and polished , to become glass . The resulting glass is thin , super-strong and scratch resistant . Apple already uses sapphire crystal in the Touch ID fingerprint scanner on the iPhone 5S and 6 , as well as to protect the phones ’ camera . The Apple Watch and Apple Watch Edition both have sapphire glass screens , while the Sport version has a strengthened Ion-X glass screen , which is thought to be more shatterproof . If the price of manufacturing the glass drops , it could potentially replace Gorilla Glass currently used in most high-end smartphones . The glass is made from synthetic sapphire , which is created by applying heat and pressure to aluminium oxide powder , before the crystals are processed to remove impurities . The tiny round disks created are ground into shape , and polished , to become glass . Sapphire glass is said to be twice as tough as normal glass and almost as hard as a diamond . The regular version , which costs from $ 549 ( £479 ) and the Edition watch , from $ 12,000 ( £8,000 ) both have sapphire glass screens , while the cheaper 'Sport ' version , costing from $ 349 ( £299 ) has a strengthened Ion-X glass screen , which iPhoneFixed describes as ‘ more shatterproof and impact resistant than sapphire glass ' . To test the durability of the screen , it was rubbed against a stone wall and then with a coin , before being ‘ scratched ’ by a key . The video capturing the attempts at destruction , shows no scratches were achieved to the screen . It also withstood being rubbed with abrasive sandpaper at some force and hit by a hammer – albeit not very hard . The video showing the attempts at destruction , shows no scratches were achieved to the screen , even when a power drill was switched on and dragged across it ( pictured ) But most impressive , was the screen ’ s ability to withstand an electric drill being dragged across its surface , without leaving a mark . The test led iPhoneFixed to claim : ‘ sapphire glass is pretty strong and virtually impossible to scratch ’ . Rumours abounded that the iPhone 6 would get a sapphire screen , but it didn ’ t , possibly because the material is expensive to make when compared with standard of tough Gorilla Glass . The test led iPhoneFixed to claim : ‘ sapphire glass is pretty strong and virtually impossible to scratch ’ . Apple has revealed it will only accept online orders for its much-anticipated watch which goes on sale on the 24th April . The firm will show off the watch to the public for the first time from tomorrow at its retail stores and several special popup stores around the world . From tomorrow morning , customers will be able to pre-order their watch online . 'Starting Friday , customers can try on Apple Watch , Apple Watch Sport or Apple Watch Edition to find the model with the size , finish and band to best fit their personal preference and style , ' the firm explained . 'Everyone visiting an Apple Store will be able to view all three collections and get hands on with Apple Watch Demo to browse and edit different watch faces , and learn about Apple Watch 's health and fitness features , Digital Touch , Siri and more . ' Based on a survey in the United States on consumer interest in buying the Apple Watch , BMO Capital Markets has cut its estimate for sales to 39 million units though September 2016 .
Two out of three versions of Apple have sapphire glass screens . Test showed how durable the material made from synthetic crystals is . Endured being sanded , keyed , rubbed , struck by a hammer and drilled .