I have those. A lot of them! I like them, their quality is about the same as majestics, milanos, ect, but I'm no expert so I can't say if they're above or below.
Beware of different versions! According to the small amount of info I've gathered there has been at least two different productions in different factories.
One version is thicker than the other (fits 19 instead of 20 in a rack), has a more papery feel to the labels, and has really sharp edges and can stand on edge just like Paulsons! The sharp edges are a pluss, but the papery labels suck and the thickness is of course an issue. This version tends to have edge spots all the way to the label, but I'm not sure if this is the true telltale sign. I have a bunch of samples of this version.
The other version (the one I have) has beveled edges just like majestics and milanos, really consistent width so the stacksizes all have equal heigh (unlike majestics and milanos), and textured labels. The edge spots do not reach the label on these.
The colors also slightly differ between versions.
I am not at home, but I think I might have some pictures to show the difference. If so I'll upload later.
Make sure to get samples, so you 1) know you like them and 2) know which versions you'll get. I had lengthy email conversations with several webshops before I finally got a set with all of the same version.
They are, from what I can tell, china clays. Whether or not that means they are plastic is of course another question

but they come with the factory dust and really pop after being oiled, just like other
CC:s.