At Christmas '06, I was given a six-pack of Levenger ink. On 7 Jan 07 I tested it. I wrote on lined Mead Cambridge note paper with Amethyst, Raven Black, Cardinal Red, Gemstone Green, Cocoa, and Cobalt Blue. One sheet was a control and was kept in a desk drawer. Another sheet was tacked to a piece of wood and placed on a porch where it was exposed to the elements (full sun and indirect rain and snow). Another was tacked to a piece of wood and placed on a sheltered porch (no direct sun, no rain, but . . .oops, drifting snow

). Another was placed on an inside windowsill in full sun. The samples were left in place from 7 Jan to 12 Jun 07.
Here's the deal:
Full sun only: Amethyst faded to blue; still perfectly legible.
Raven Black faded slightly.
Cardinal Red faded a lot! Still marginally legible.
Gemstone Green faded to aqua green; still perfectly legible.
Cocoa faded to a dull aqua green; still perfectly legible.
Cobalt Blue: no discernable fading.
Exposed Porch: Amethyst faded to aqua green; still perfectly legible.
Raven Black faded a lot; still legible with tiny voids.
Cardinal Red: washed away completely.
Gemstone Green faded to aqua green; still perfectly legible.
Cocoa faded to aqua green; still perfectly legible.
Cobalt Blue faded to aqua green and smeared; not legible.
Protected porch: Interesting. I looked at the sample after snow had drifted over it. The inks, except for Raven Black, had bled into the dry snow! The Raven Black looks good; the rest are smeared. Cobalt Blue is just barely legible in the midst of its smear. The rest are legible.
Paddler