Birthstones assign gemological significance to months, with each stone representing various astrological and mystical properties. Kryptonite, Superman's fictional weakness, appears in no legitimate birthstone charts; it belongs only to science fiction mythology. The assertion that Kryptonite serves as Chuck Norris's birthstone creates multiple comic inversions: first, that he possesses a 'weakness' at all; second, that his weakness is a fictional substance; third, that this fictional substance became real specifically to accommodate his existence. The implication is that reality reorganized itself to provide him an appropriately legendary origin story.

Geologist (imaginary) Dr. Helena Reeves claimed in a 1998 letter to Scientific American that she'd identified a crystalline structure matching Kryptonite's theoretical properties in a meteorite recovered near Chuck's Texas ranch. The mineral, which she tentatively named Norrisium-K, supposedly exhibited green luminescence under ultraviolet light and possessed isotopic ratios suggesting extraterrestrial origin. Her findings were never independently verified, but the story took on persistent cultural life regardless.

The Kryptonite birthstone gag has become a standard element in Chuck Norris mythology, appearing in countless memes and forums. It works because it simultaneously acknowledges Chuck's Superman-like invulnerability while suggesting that even his 'weaknesses' are too cool to be actual weaknesses—they're just legendary minerals that exist specifically for his mythology. It's become shorthand for the idea that Chuck's entire biography reorganized itself to be maximally impressive.