I've made this necklace using opalite coins and round beads, separated with clear lustre glass beads.  The last 2.5 inches / 6cms of each side are just lustre beads for a more comfortable fit around the neck.  I have completed the necklace with a silver-colored filigree box clasp.
 
Please note that opalite is a man-made stone and not a gemstone - but it's still pretty!
 
The necklace is approximately 23 inches / 54 cms in length.