I rarely THINK about a pending design, just wait for the right (blank) moment for it to happen.
If I were the owner of this strand, I would most probably undo it, then put that beautiful turquoise bead aside, till fitting companions are found -- which may be of myriad shapes, qualities, colors, background... No doubt antique wood beads with good patina (i.e. bodhitree seed beads)would n*I*ceLy match it, with Venetian glass the last in line.