Ottoman (?) kard for comment
 

I need some help on this ottoman kard.
The handle is mother of pearl.
How old do you believe it is?
From what region of the ottoman empire?

It would be interesting to see a blade, is there a repeating pattern along the spine?
By some indications, I would call Montenegro, Boka Kotorska, the place of production.

More photos

Lets proceed by elimination
It is not from the Balkans
It is not from North Africa

Thank you for your answer Saracen.
What is the indication that makes you think about Boka Kotorska?

Hi, vasilisnik. Thank you for the additional photos and I apologize for the long wait for my answer. I had a hard weekend:).
Since there is no characteristic ornament on the blade, I think about Boka Kotorska by the design of the scabbard.
Scabbard is either produced there, or produced by a master who has received the skills to make them in one of the weapons centers of this region.
The shape of the end of the scabbard (Chape?), as well as the shape and location of the movable ring tell me about this.
This spherical form chape of the scabbard, archaic for the Ottoman Khanjars, was preserved by the 19th century only on bichaqs from the Bay of Kotor region.
The bichaq itself may be a little older and probably this is not its first scabbard.
The ornament on its handle looks Greek to me, but this ornament is also often present on the handles of knives from the Boka Kotorska.

Thank you for your answer Kubur.
Are you aware of the use of mother pearl for dagger handle material anywhere in the Ottoman Empire?
I have searched for similar handle examples but without luck.

I agree with you that there are similarities.
The scabbard locket, the suspension ring and the spherical scabbard ending are similar.
There are major diferences too.
The scabbard shape is different and there is no use on niello.
Furthermore the pattern of the scabbard ending looks very turkish to me.

I think there are much more similarities than differences :) and these similarities give more certainty in the tradition of production than differences. In addition, the shape of the scabbard is determined by the shape of the blade, this may explain the differences in the shape of the scabbard of your bichaq from the traditional form of the Boka Kotorska scabbard.
There is some eclecticism in the design of the scabbard, but I find it difficult to determine the pattern at the ending of the scabbard. Turkish I see only the composition of the ornament on the side where this pattern is. But such a composition seems to me to be common and characteristic of Ottoman objects from different regions.
The curly ornament on this side looks typically Greek for me, the same ornamental motif is also on the handle of your bichaq, it can also be found on the scabbard from Boka Kotorska. The Anatolian version of this ornament is more abstract and more saturated, as in the example below.

The opposite side of the scabbard is also decorated in the Greek tradition: repeating sectors with plant elements. As on the scabbard of the yataghan from Ioannina shown in Robert Elgood book "The Arms of Greece..." on page 140. And on the bichaq scabbard in the photo below. In general, I still think that you have a very interesting bichaq originally from the Western Balkans. I only doubt that its handle is made of mother-of-pearl. Can it be a specially treated horn?

The hilt is brittle, as seen by the crack; mother of pearl is notorious for this sort of fragility. I don't think you could achieve the iridescent luster of the surface on horn.

The scales on the handle seem to me too large to be mother of pearl.
I do not know a clam whose shell has such a thick layer of mother of pearl.