Hi Mike,
Almost all diamond inlay's tend to float.
Some a bitt more than others, sometimes you need to apply some light pressure in one of the corners to make it move.
Not one manufacturer fixed them so they would not move.
The diamond inlay has on his back two pins wich are inserted throw the holes of the bakelite handle, obverse side, and then folded back. So at the beginning, just after assembly they would be very tight held in place, but as time passes by, the folding back loosens a bitt with as a result the wiggling of the diamond inlay.
When you encounter a knife these days with a diamond inlay wich is firmly held into place is IMO a glued one ore maybe a newly assembled knife. Sometimes dealers get differentoriginal parts wich on their own are still good and assemble it into a new knife OR have upgraded a battered knife with new bakelite handles, the diamond and rivets. Always look then at the overall appearance of the knife is my advice at that moment.
Hope this clarifys it a bitt,
wizardelf