Effetre Copper Green - well known for being one of the more "reactive" glasses. However, a recent introduction to a certain gecko got me thinking about using it for it's natural colour. It matches very nicely to a rather handsome gecko that I just met, (no really - I have friends w a houseful of lizards).
I thought I'd better get a handle on the colour, the reactions, and oh yeah, as I remember - it reduces in the kiln.
This is a self-coloured spacer - Copper Green. It comes out of the kiln with a dull, grey layer - quite unappealing.

As with the turquoise glasses - when they do this, I soaked the beads in CLR. I was a little short of it, so I actually used a solution of about 50% CLR and 50% water. Generally - I only have to soak beads for an hour or so - this diluted solution (and maybe the layer on the copper green is tougher?) took longer - I let them soak for about 2-3 days. I could see improvement after the first 3 hours - but I wanted more - so I left them longer.

Above, this is the same bead, post CLR'ing. (CLR is a cleaning solution for removing Calcium Lime and Rust. It is now also a brand for other cleaning products. You want the original. I've tried cheaper brands - they don't work as well.)
The colour is very close to what I had in mind - a soft, pale green.
Next - also a solid Copper Green bead - this one was deliberated reduced. Note the large patch of red that it has developed.

And, here is the same bead, post-CLR. The red patch is much more vivid and vibrant. I like the hue much better.

This is a base of copper green, with EDP (Effetre Purple) dots.

And below - post CLR. I actually like it less now - less character.

This is a base of EDP, with copper green dots. Note the truly magnificant separation effect - making the single copper green dots look like a dot on dot effect.

Post CLR, again, I think it has lost some character.

Ivory base, with Copper Green dots, and ivory dots again.

Post CLR - the copper green is brighter, but I think I liked the first version better.

So - an extended soak in CLR will take off the dull, metallic haze - which is what I wanted to know.