| Credited cast: |
 | Jem Stansfield | - | Himself - Presenter |
| Rest of cast listed alphabetically: |
| Bob Cava | - | Himself - AT&T Bell Labs, New Jersey (archive footage) |
| Boris Feigelson | - | Himself - Diamond Scientist (archive footage) (as Dr Boris Fiegelson) |
| Don Huffman | - | Himself - University of Arizona (archive footage) (as Prof Don Huffman) |
| Andy Kaldor | - | Himself - Exxon Research & Engineering (archive footage) (as Dr Andy Kaldor) |
| Henry Kolm | - | Himself - Massachusetts Institute of Technology (archive footage) (as Dr Henry Kolm) |
| Harry Kroto | - | Himself - University of Sussex (archive footage) (as Prof Harry Kroto) |
| Jerry Kulcinski | - | Himself - University of Wisconsin-Madison (archive footage) (as Prof Jerry Kulcinski) |
| Simon Lawson | - | Himself - Gem Defensive Projects, De Beers (as Dr Simon Lawson) |
| Stephen Lussier | - | Himself - Marketing Director, De Beers (archive footage) |
| Mark Newton | - | Himself - Oxford University (archive footage) (as Dr Mark Newton) |
| Harrison Schmitt | - | Himself (archive footage) |
| Rick Smalley | - | Himself - Rice University, Houston (archive footage) (as Prof Rick Smalley) |
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