Norway

The jeweller emerged from the backroom bearing a large blackbox, glittering with precious gems. I thought I'd schooled my face to stillness, but jewellers' eyes are sharp.

"Don't be too impressed--only one in sixteen is real. Find which ones, and they'll tell you what you need to know."

Next I knew I was staggering under the weight of the box, which he'd closed, locked, and thrust into my arms. "Of course, I can't make it too easy for you, so you'll have to do it with the box shut."

"H...How?" I managed to get out.

"Tomography." He ducked behind a counter, pulled out some electronic equipment scarily reminiscent of Bond's tabletop encounter with Goldfinger, and dumped it on top of the box. "Laser...and detector. Shine the beam in, and note where it comes out. It goes straight through the fakes, but the real ones absorb or deflect it."

"Wha...?"

"Sorry, I'm busy, you're on your own." A large tome joined the pile of stuff on the box in my arms, and I peeked at the spine as he shunted me out the door. "Blackbox manual", by Emacs G. Ame. "If you get stuck, look in here. 'K, good luck!" With that he closed the door behind me, and I found myself, arms full, alone on the street.

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     4 1 H                              H H R H H
  3- - - - - - - -3                 - - - - - - - -
   - - - - - - - -4                 - - - - - - - -4
   - - - - - - - -                 3- - - - - - - -1
   - - - - - - - -                 2- - - - - - - -2
  2- - - - - - - -H                 - - - - - - - -
  H- - - - - - - -1                1- - - - - - - -
   - - - - - - - -                  - - - - - - - -
   - - - - - - - -                  - - - - - - - -
         2   R                        3           4

     4         6                    4   H 2 3 H H 5
   - - - - - - - -                  - - - - - - - -
   - - - - - - - -6                1- - - - - - - -1
  3- - - - - - - -                 4- - - - - - - -2
  1- - - - - - - -                  - - - - - - - -
  2- - - - - - - -                 R- - - - - - - -
  3- - - - - - - -1                 - - - - - - - -5
   - - - - - - - -                  - - - - - - - -
   - - - - - - - -5                 - - - - - - - -
     4     5 2                      H H     3