Chiplab has two product families - "clay" and "clay composite". Like almost all chips marketed with "clay" in the name, the word "clay" is meaningless here. Both product families are metal-slugged injection-molded plastic, and are completely unlike the compression-molded plastic chips that we refer to as clay, i.e. Paulsons and TR Kings etc.
That said, their "clay" chips feel much more clay-like than their "clay composite" chips. Nothing at all like Paulsons, but quite a bit different from, and nicer than, typical metal-slugged chips such as dice chips.
I don't encourage anyone to buy them, as I think there are probably better options for the price. But I do encourage anyone who's at all interested to order their free samples and feel them for yourself. And if it turns out you really like the way they feel and the price works for you, then more power to you.