Aluminium oxynitride (AION) – marketed under the name ALON.
The material is 85% as strong as sapphire, is a ceramic and has similar structural and optical properties to sapphire.
Image kindly reproduced according to the licence at:http://en.wikipedia.org/wiki/File:Star-Saphire.jpg
Research has shown that it is able to withstand armour piercing rounds fired from Russian and Browning sniper rifles. It is stronger and more lightweight than existing bullet proof glass.
Its strength lies in its structure. Regular bullet proff glass is from layers of laminated glass and polycarbonate.
The new bullet proof glass is made from a layer of ALON, a layer of toughened glass and a polymer layer.
Article adapted from the article ‘Tougher than a speeding bullet’ that appeared in New Scientist magazine on the 29th October 2005 on page 25.