It is presumably the scarcity of Green Kryptonite, combined with its crushingly debilitating effect on Superman, that has motivated a number of villains to find ways to synthesize it. Lex Luthor creates the 1st synthetic kryptonite in February 1950 by ingeniously fusing together â€œa mammoth pearl from one of the giant oysters miles down under the seaâ€; â€œa couple of handfuls of dust from the dark side of the moonâ€; â€œpollen from the man-eating homocessandi plant deep in the Asiatic junglesâ€; and â€œa bit of the rare chemical binarium, preserved in the soil by a thousand years of glacial frostâ€ (Act No. 141: â€œLuthorâ€™s Secret Weaponâ€).
Dr. Vallin devises a formula for synthesizing green kryptonite in January-February 1952 that calls for stockpiling gold, silver, lead, and bismuth and then â€œfusing the... ore with acid and crackling electricityâ€ (WF No. 56: â€œThe Superman Pageant!â€).
A third method of synthesizing kryptonite, successfully employed by Lex Luthor in August 1953, is based on Luthorâ€™s observation that:
Each piece of metal that strikes Supermanâ€™s invulnerable body undergoes a slight chemical change! To a minute degree, it acquires the properties of kryptonite, but its presence is so faint that it can only be detected by means of a spectroscope!
Kryptonite is the one material that can harm Superman! By refining tons of this metal, Iâ€™ll be able to extract kryptonite---just as radium is obtained by refining tons of uranium ore! [Act No. 183: â€œThe Perfect Plot to Kill Superman!â€].
The Fixer, and a renegade scientist, creates a batch of synthetic kryptonite and exposes Superman to it for days, until the Man of Steel manages to escape by burning a hole in the floorboards under the kryptonite. By then his mind has dimmed and he can not remember who he is, except by temporary exposure to the moon's rays. Later, an accident with a powerful radio-therapy machine "activates Superman's numbed memory cells and cures his split personality" (S No. 77, Jul 1952: "The Greatest Pitcher in the World").
In November 1955, Luthor creates another batch of Synthetic Kryptonite and appears in disguise at Superman Land, billing it as artificial and attempting to get Superman to autograph it (Act No. 210: "Superman in Superman Land").
Red Kryptonite has been successfully synthesized on several occasions, notably by Professor Benet, a Nobel Prize winning chemist, in August 1962 (Act No. 291, Aug 1962: â€œThe New Superman!â€) and by Lex Luthor in April 1964 (S No. 168, Apr 1964: â€œLuthor â€“ Super-Hero!â€ pts 1-2).
In addition to synthetic versions of Green and Red Kryptonite, there are other versions of Kryptonite which are only found as Synthetic Kryptonite, these are X-Kryptonite, Slow Kryptonite, Magno-Kryptonite, and Mutated kryptonite.
Finally, there are also two hoax variations of Kryptonite which are also synthetic, they are Silver Kryptonite and Yellow Kryptonite.
(See the Kryptonite entry for more information on these synthetic forms)