The news isn't reporting when the ring was appraised or valued, but it would be interesting to know the date that it was done ( & compare that to the supposed pick up date by GF), and if they have a requisition/approval process for that and the timeline of that itself.
Based on the GF's previous willingness to cooperate, it would seem more likely of him to say that he didn't pick up/recieve the ring, instead of saying he doesn't know where it is. It's that gray area of telling the truth without fully revealing himself - which is a bit suspect. At the same time, I don't blame the man for wanting to be vague if this is new information to him as well, or if it isn't - having to wrap his mind around the idea of that ring sitting in the sock drawer = Gabe.
Also, not all jewelry is etched, appraised, or insured or bought at mainstream stores. The amount of data out there (Insurance claims, stores, pawn shops) in TX alone would be massive and getting 100% co-op- uff) Besides, if it was passed within the family, tracking that would be difficult.