I've been working recently on such a wet/dry chart, and it is finally ready for public consumption. Many thanks to Stefan for helping me sort out which of my Gossamer spools are Primrose, Light Yellow, and Lemon Yellow. I wrapped two layers of each thread about a bronzed hook and photographed both hook and spool simultaneously. The white balance of my camera was calibrated, and colors in the photos are, to my eyes, very close to those on the spools.
The chart is quite large and should be zoomed in for best viewing of the wet/dry hooks. For example, when viewed at 100% size, each spool looks something like this:

The full chart is too large for viewing here, but it can be viewed, downloaded, and saved at: https://app.box.com/s/y34hr9vpfzs54lv2byhj3xww1dhicpdi
I made a similar chart of spools only (no hooks), which is available at:
https://app.box.com/s/3pmuu5kg393fpzo6k3kts6hfsrzqg8ak
I realize the madness of making a color chart for threads that no longer exist, but I suspect that, like me, many folks here have stashes of Pearsall's Gossamer that will last for many years. I hope these charts are helpful.
Cheers,
Phil