The Monthly Film Bulletin wrote: "The settings are good, especially those in the laboratory showing the Professor and Joseph manufacturing the diamonds. There is some first-class acting by Lesley Brook as the Professor's daughter; Renee Gadd as the foolish but faithful friend provides some genuinely comic relief, and Noel Madison as the ruthless villain of the piece grips one's attention from start to finish. ...Not suitable for children or adolescents."
Kine Weekly wrote: "Sensational crime thriller turning on a fantastic but gripping theme. ... Noel Madison presents a pretty portrait in villainy as Joseph; James Stephenson and Wilfred Lawson are good as a couple of crooks; but George Galleon is not too sure of himsell as Tony, Lesley Brook is colourless as Helen, and Renee Gadd is inclined to force the pace in a comedy role. ... In its pursuit of thrills, this crime melodrama has scant regard for reason, but the realism with which the thrills are enacted and draped with pseudoscientific detail thrusts the colourful rough-stuff well and truly home."
The Daily Film Renter wrote: "The Teddington studios have gone all out to make an unvarnished thriller for the purely popular market, and achieve their end in a subject which, while somewhat naive by critical standards, nevertheless has the right ingredients for the purpose. It has thrills and plenty of action, weird machinery and a certain sinister atmosphere, the latter owing to sincere acting by the main crook element, with a deal of artless humour and confected romance to round off its mass appeal."
Picture Show wrote: "It is all rather vague and rambling, with the villain (the diamond maker) meeting his death through climbing a pylon and being electrocuted." == References ==