Whatever size they are, they look like rocks with a glaring, deep blue colour.
Powers and abilities
Effects on Kryptonians
Blue kryptonite strips Kryptonians of all their powers, making them mortal and, thus, susceptible to damage and pain as with any human. However, it also renders them immune to the effects of green kryptonite.
Effects on Bizarro
Blue kryptonite magnifies Bizarro's powers to such an insane degree that it causes him to shake and explode. Brainiac remarked that it causes an exponential power increase.
Effects on humans
Blue kryptonite can drastically improve the health of anything organic, such with water, crops, and humans. Continual consumption of blue kryptonite puts humans in a perfect state of health.
Blue kryptonite can be counteracted with lead.