Looks like plain ol' pine from the photo. With the wood being inside, there should be a minimum of movement, I would think unless they open the doors for a long time. But with low humidity of your area, shouldn't be a problem. Others who live in the West might have experiences they would share.
We have a Mexican restaurant in town that built their own booths and tables. Plywood and 2X4s with a scorched exterior and clear poly.
There are books and videos on using 2X4s for building just about anything.
A diamond is how coal reacts under pressure.