Martine, I know a few gemstones because of beads I have bought. I bought from somewhat reliable sources and I keep the labels on the strands. Some minerals are more distinctive than others. I also study beads at bead stores, even if I don't buy them. I read the gem pages at Rings and Things. I look at lapidary websites that show cut slab. Here is a favorite website (I've never done business there) where I've spent hours looking at photos. The photos of gem slabs change frequently. link below

Chrysocolla is new to me. Fascinating. Beautiful. Maybe I have some, who knows.

Turquoise has me completely confused. I buy known Chinese turquoise, the real stuff, from bead stores and can recognize it fairly well. But mostly I buy turquoise colored stone beads at thrift stores, as long as it is attractive and looks like real stone... who knows what it really is. I have a lot of it and don't know what to do with it.