I don't know about you, but I get sooooo frustrated trying to figure out which species a particular Lithops belongs to. If the nursery or grower doesn't tell you, it gets very complicated, particularly since many Lithops of one species look like identical twins to Lithops of other species! I still have no idea if some of my "French Blues" are L. julii or L. salicola. So I just keep calling them "the French Blues". And don't get me started on Cole numbers....
But one site on the Internet has been very helpful:
Nick Rowlette has done a great job with basic instructions for Lithops-guardianship, and has put together a fantastic photo gallery of all sorts of species, their variations, you name it. It's a real gold mine for Lithops lovers who struggle to identify their "living stones". Just click on the "Gallery" section. Way to go, Nick!
One of my favorite species is Lithops lesliei. The intricate dots-and-lines patterning, and the gorgeous earthtones of this species never fail to charm and delight. Here are a few of my "Leslies", in pot I made particularly to show off their patterning--
And here is one of my L. lesliei albinica, newly releaved: