What kind of necklace is this?

Looks like it might have some refractive properties; it might be made of the stuff they use for fiber optics. In recent years that has been used in jewelry, because it catches the light (much like a star sapphire, but showing a single line rather than a star). Looks older than most fiber optic jewelry I've seen; but for comparison only:

 

The question is non specific,but I'm guessing it's about the beads.Most likely the beads are fiber optic beads.

 

Reminds me of Gypsum or Feldspar (moonstone)

 

Too old for fibre optic. Try moonglow beads.

 

They do look like moonglow, but aren't moonglow beads plastic or lucite?
These don't look plastic to me.
I would say stone, possibly gypsum like quirky said. I don't think moonstone, because of the striations. See the one that broke.

@Kingjoker when you put these to your face are they cold or warm?

 

Didn't notice the broken bead earlier,most likely selenite/gypsum.

 

There are cold

 

Then not plastic.
Stone or glass.

 

Hollyblue, I agree, selenite.

 

Moonglow was made in both plastic and glass

 

Indeed it was!