From the reverse, you can see some really interesting things about the naja. First, the tri-wires
are clearly hand-drawn (note the unevenness of the flat surfaces). Second, the thin wire set in the middle is not actual ropework, as would be expected in a piece from the 1920s or later. Instead, it is a single wire that is smooth on the back, which means that the "twisting" pattern on the front was done by scoring with a chisel or file. Not easy to do, especially with such a thin wire. And finally, the label on the back is some sort of collection number, most likely from a museum. It could have been left to a museum in 1965 (hence the "65" at the beginning) and then deaccessioned later on. Since many museums started life as large private collections, and were run as such up until very recent times, it is not surprising or uncommon to find pieces that show signs of being part of one at one time or another. Though this necklace is of museum quality, a local historical society or non-Indian museum would have no use for a piece like this and would deaccession it to raise funds for more appropriate acquisitions.
The higher beads (on the left) are slightly smaller and rounder. At some point, probably pretty early in its life, this necklace either broke and was restrung with some smaller beads, or was lengthened (quite a bit) with the smaller beads. The small beads are quite old and well-done, and it is a time-honored tradition among the Navajo to maintain their necklaces by restringing them when necessary, so it only adds another chapter to the interesting history of the piece. Also, two of the blossoms are missing a petal, with only two instead of the original three. We don't know exactly what happened along the road, but clearly this is a piece that has had an eventful life.