Tom Swift Among the Diamond Makers; Or, The Secret of Phantom Mountain

Tom Swift Among the Diamond Makers, Or, The Secret of Phantom Mountain, is Volume 7 in the original Tom Swift novel series published by Grosset & Dunlap.

Tom Swift flies his airship to the mountain tops of Colorado to seek for the secret of the Diamond Makers: criminal scientists who have figured out the formula of manufacturing a limitless fortune in diamonds. But these rogues will stop at nothing to keep their secret. Tom & friends are soon captured and left to die in a collapsing mountain.

Although the story still revolves around invention, Tom did not have any part in the invention. In this story, the major invention, and plot device, is a diamond-making machine, utilizing the power of harnessed lightning. Unfortunately for Tom and friends, they were never able to get close enough to the machinery to determine the secret to making diamonds.

In the previous book Tom Swift met a fellow named Jenks on Earthquake island who claimed to be have knowledge of a method for making Diamond. As is often the case a small plot thread from a previous book becomes the central plot point for the current one. Mr. Jenks has returned looking for Tom Swift's help in locating the mysterious Phantom Mountain where he invested in some men who demonstrated the ability to make diamonds. After they took his money they sent Jenks on his way. It looks like a total scam except they left Jenks with several diamonds that Tom Swift had appraised for more than the value of the money they stole.