The new nanocrystalline spinel is made of the same materials, magnesium aluminate (MgAl2O4), but the grain size has been reduced to 28 nm.Apparently the Army has also been experimenting with Spinel, stating that they're getting good results with the material and there are many advantages to it. (pdf warning)
the first gemstones to be synthesized, and harder* than spinel. The approach they use to synthesize this spinel is radically different from any way I know of to synthesize gem crystals and makes me wonder if new ways of creating synthetic gemstones will hit the market. Not quite beating swords into plowshares, but perhaps a dividend.
Light weight transparent armor in sizes up to 16” x 40” Weight savings and thickness reductions of 50-60% over current systems Reduce cost per square foot by 20-50% for Spinel ceramic plates for armor Superior resistance to scratching, sand erosion and fracture due to rock strikes will provide major replacement cost avoidance payoffs Operations and Support (O&S) cost savings will be achieved as a result of reduced vehicle maintenance and increased window service life Reduce Spinel manufacturing costs by up to 50%
*On the geologist's, or Mho's hardness scale, Spinel has a hardness of 8, while sapphire is hardness 9 - second only to diamond at 10. The watch crystal on my everyday watch is a clear synthetic sapphire and two years of wearing it hasn't left a single scratch on it. Hardness is a poor indicator of how tough a mineral is; it's only what stone can scratch another. Some relatively soft stones, like jade, are phenomenally tough to break.