Congrats on a great piece.
Unusual to see such different stone used for the grip scales and 'bolsters'.
Mostly the stone used is Jadeite or Nephrite. I believe that even within the 'term' Nephrite there is a wide variety of colours and types ranging from opaque semi single shade to near trasparent with milky inclusions. In other words both types on your fine dagger could be Nephrite (I think it probobly is).
As for date, I believe these (of the style you have) go right back into the 19thC.
The scabbard would be a relatively simple fix. Recover with thin leather or velvet. As the end mount is undecorated, a replacement upper band would be a fairly easy job to fashion. You could even make the brass pendant for the top of the hilt!
I have to say that this type of Pesh is one of my all time favourite dagger types. I think they are absolute perfection of both form and function.
Heres mine, 35cm total length.
