http://www.bmwblog.com/2017/11/02/bmws-bowers-wilkins-worth-price-audiophiles/
"The Bowers & Wilkins system consists of 16 speakers, 1,400-watts, 10 amplification channels and even Diamond Dome tweeters. That?s right, Bowers uses diamonds in its tweeters because it provides the best sound clarity. Obviously, the wafer thin, dome-like layer of diamond in the tweeter isn?t made from the same pretty stones in an engagement ring, but they?re made from diamonds nonetheless."
5 and 7 series.
More at the link.
"The Bowers & Wilkins system consists of 16 speakers, 1,400-watts, 10 amplification channels and even Diamond Dome tweeters. That?s right, Bowers uses diamonds in its tweeters because it provides the best sound clarity. Obviously, the wafer thin, dome-like layer of diamond in the tweeter isn?t made from the same pretty stones in an engagement ring, but they?re made from diamonds nonetheless."
5 and 7 series.
More at the link.