BTW, was that your own work -- or photos of others' work?
Sadly, I had a nice supply of blue-gray Georgetown chert, and some good samples of various Edwards Plateau browns -- but it was in our garage in MA when we had a fire. Now, it's all heat-fractured... :-(
All my work. I have a ranch covered in the Caramal coloered chert and have some real nice Edwards Gray. No heat treating needed on either.