The terms scratch proof and scratch resistant are different by definition, but used synonymously by manufactures to promote their products. Scratch proof, if taken literally would mean that the product is able to withstand any kind of abrasion and not bear any scratches. However, it is impossible for manufactures to provide this kind of guarantee for delicate items like watches, eye-glasses and others. Scratch-proof, therefore, stands for more durability than scratch-resistant products.
Scratch resistant, on the other hand essentially means that the product is able to withstand minor scratches.
There are two ways to prevent scratches on delicate surfaces. This is possible either by reinforcing the material itself so that it can withstand damage for long, or by coating the surface by an external film or coating that shields it from damage.
Watches and Rings
Some manufacturers advertise watches made with reinforced glass like mineral glass or sapphire crystal as scratch proof products. Though not entirely scratch proof, sapphire crystal is more resistant to scratches than ordinary products and used only in high end expensive watches.
Titanium is a tough metal, non reactive to corrosive substance and hence ideal for making jewellery, like rings for regular wear. Rings made of titanium are also considered more scratch resistant than other metals.
Prescription eye-ware and Sunglasses
To make surfaces of eye ware scratch resistant, an external coating is generally applied on it that prevents minor damage. This is a very thin coating is made from diamond like carbon and polycrystalline material which does not hamper the vision of the person wearing it. This coating only prevents minor damage and does not offer a long term protection. Other products that come with this protection include camera lenses, iPods and MP3 players, computer screens, DVDs and CDs, cars, and so on.
Thus, the difference between scratch proof and scratch resistant is more a matter of semantics than anything else. It is best to take proper care these items, and store these products in a safe place to avoid scratches. Once damaged, it is not possible to repair these scratches and most likely the item will need to be replaced.