It's done! I used the purl bee granny square tutorial to make this. I think you could easily make one of these even if you don't know how to crochet already. These pictures are of the afghan unblocked. It's currently soaking and will be blocked tomorrow. The finished size pre-blocking is about five feet square.
I used 10 skeins of Noro Iro plus a bag of unknown recycled brown wool I found in the stash for the border. I just crocheted until I ran out of the Noro, then switched to plain double crochet (I think) for the border and continued until I ran out of the brown yarn, which I held doubled. If you don't already know this, crochet really, really eats up yarn. I think I had a whole sweater's worth of the brown yarn.
I used a size J hook, because it seemed to be about right and I had one. Gauge is pretty irrelevant with an afghan, as long as you like the fabric. I can honestly say I loved making this, despite the problems I had and the massive amount of ripping I did to solve them. (After I got the whole thing done and the ends woven in last night, I discovered a mistake with a corner only inches from the beginning. It doesn't throw off the shape, though, and I'm not about to rip the whole thing again, so I am embracing the error as proof that it was made by human hands and not a machine.)
The tortoise came over to check it out during the FOto shoot. I think he likes it.
[Endangered California Desert Tortoise, which can't be re-released into the wild. I have a permit for him. My aunt rescued him from another owner more than 30 years ago, and he was already an adult then. I've had him for the past three years, since my aunt moved to Colorado, so we know he is approaching 40, at least, and may be much older. No one knows how long they live, but they are known to live at least as long as humans, and probably longer. I'm going to have to put him in my will.]