This Mexican turquoise bead from Two Cranes has a lovely green-tinged hue and rich brown matrix that work very well with copper. I kept the necklace simple, using more Mexican turquoise along with some rough copper spacers and a copper clasp that I scratched up a bit on purpose so it will darken up more quickly during wear.
I love turquoise with copper (obviously) and have sold several pieces that I've been tempted to keep but, well, when I sell one, I can buy stuff to make more. The piece at left is another Two Cranes Mexican turquoise pendant that I put on an adjustable leather cord finished with copper wire and some handmade copper headpins. This pendant has a more striking green hue which, to be honest, I couldn't figure out how to match, hence the leather rather than beaded necklace. Turquoise with leather and copper seems a quintessentially Southwestern combination, though, and I'm surprised that I don't see it more often. I have one piece made in this style that I've kept for myself (despite the frequent temptation this is actually a rare occurence), and the leather has worn very well for well over a year, darkening along with the copper as I wear it. I use a high-grade Greek leather, which surely makes a difference.
The necklace at right uses a Chinese turquoise pendant (not Two Cranes) with a beautiful "cascading" matrix. Turquoise matrix features so often look like water features, which is apropos given how the stone is created. I set this one on 16-gauge copper with wirewrapped leather and a front clasp that I shaped and hammered myself. I've used this clasp style in several pieces (including the aforementioned piece in my personal collection), but I later found (after conferring with the buyer) that it doesn't work well with a smaller, lighter stone: it pulls it off balance. I re-balanced this necklace for the buyer by adding some small copper-wrapped turquoise "charms" to the other side; she was pleased, especially when I threw in some matching earrings for free.
