Is it a keris handle and when yes from where?

[Sajen]

This (sea?)ivory handle is from the collection of a well known collector in Germany. It's IMHO a very nice and unusual handle but is it indeed a keris handle? A comparable handle is shown in Bob Hales book, page 138, pic. 328.
He writes that this is a keris handle from Sumbawa, Bima and that only two handles of this type are known! Anyway, would you agree with the origin? Approx.: 7 cm high.