I did a little digging prior to buying my Speedmaster and I found this interesting -- from the Omega site.
Question - Why is the Speedmaster Professional "Moon Watch" fitted with a hesalite crystal?
Answer - The Speedmaster Professional is worn by astronauts in outer space. When NASA chose this watch, they requested a hesalite crystal, which "unlike a sapphire crystal" does not break into tiny fragments on impact.This feature is very important for astronauts, as the tiny fragments of a broken sapphire crystal would pose a danger in a zero-gravity environment.
• Exceptional light transmission with virtually no colour bias - even in thick blocks. • Excellent resistance to outdoor weathering. • Good resistance to impact. • A high gloss, hard surface. • High tensile strength and rigidity. • Easily thermoformable with simple workshop tools. • Easy to clean. • Capable of being fully recycled.
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Last edited by andrema on Mon Apr 12, 2010 10:18 pm; edited 1 time in total
AtomicTom Senior Consigliere
Posts : 19428 Join date : 2009-08-25 Age : 52 Location : New Jersey
Makes sense ! Also if it's good enough to work in space, then it's going to work fine down here ! It is actually very cool that Omega kept the Hesalite crystal in the watch, instead of replacing it with glass. It makes it more authentic imho !..VERY interesting information !
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Northwestguy Senior Associate
Posts : 2612 Join date : 2009-07-12 Location : OREGON
The history of the selection of the Speedy is good reading. Chuck Maddox's website is excellent and as I recall has the entire saga beginning with some admin/logistics weenies going out to a local Houston Jewelry store and buying one each of about 5-6 chronos on hand. Then there is the "redo" demanded by Bulova and the American Watch companies after repeatedly failing the engineering tests. Good stuff.
Subject: Hesalite Crystal -- Why? 
Mon Apr 12, 2010 9:35 pm
Also if it's good enough to work in space, then
