It's a German product. The website used to have an English translation on it but it seems to have gone... www.joya.eu The only official site I can find in English now is the Australian one www.joya-australia.com.au
There is a book JOYA - Crystal Massage for Everyone - THE JOYA Book by Michael Gienger & Ulrich Metz. Michael Gienger is the author of lots of crystal books and has a school. I like his approach to crystals, he goes into the scientific stuff about how they work due to structure and elements, not just the new agey side of it. Ulrich Metz developed the rollers.
The wooden rollers aren't suitable for a clinic environment due to sanitation issues, so they have a more expensive plastic set available. The wooden sets are great for personal use. I use stones, and prefer to use the stones for a full massage due to the variety of sizes, large stones cover a larger area faster, but the joya routine seems to be a bit more meridians/lymphatic type thing than get into the muscle routine, though it can be good for shoulders/scap, though even then I'd prefer using stones. They work well over clothing and they can get into small areas like the forearm very well. The facial pens are used for an almost acupressure type face massage with a bit or rolling in between points.
Plus the joya rollers have the crystal properties But then you can just get a few crystal spheres and do a similar routine. I do use spheres in my routines and I tend to use larger ones than the joya rollers use. The professional rollers, I found a couple of cushiony bits inside fell off after they'd been washed in hot water and soaked in disinfectant a few times, which sort of defeated the purpose of saying they are able to withstand sanitising. Luckily the bits didn't go down the drain (they were small enough). I found this strange little plastic disc and kept trying to figure out where it came from and finally realised it was the bit out of the joya roller. Now I am just very careful to watch the disc.
If you aren't using stones or crystal spheres, the joya rollers are easy to use and a good addition to a treatment. If you are currently using stones and spheres they probably aren't going to add much.