Two window washers ... Diamonds are able to cut through glass more easily than steel is. The handheld saw, about the size of a household cordless drill, sports a circular diamond-edged blade ...

Diamonds, which are the hardest known substance, are typically used to cut glass ... yellow-tinted glass called AM-III, which is capable of leaving a deep scratch on a diamond.

Using a diamond to cut glass is not news ... and the price is unlikely to be cheap, a bulletproof window made with the AM-III could be 20 to 100 times tougher than some mainstream products ...