none more so than the one showcasing 11 rare blue diamonds surrounding the de beers millennium star. we are honored to present the de beers millennium star. >> when it was originally found, it was 777 karts in the rough, as we call it. eventually, as you know, it finished up as this magnificent polished diamond of 233 carats. >> the diamonds are kept in a special vault in glass cases. these glass cases are designed specifically to guard them from attack. >> that glass we were told by the manufacturer would sustain up to a half an hour that was seriously trying to take it with any instrument that we knew of at the time used by robbers. >> the gang attacks in the morning, when the exhibits, including the diamond vault, are open to the public. the thieves use a huge bulldozer to ram through the gate and the wall of the millennium dome, and it's unstoppable. >> this was like a tank. nothing was going to stop this. it was too big. i mean we couldn't even shoot the tires out. >> it's complete chaos inside. tourists allowed inside by police so the criminals aren't tipped off, are caught una