F. de Luzon's Moro Kris Collection

[Robert]

The plain backsides do look carabao to me. The front sides don't come out very well but are mottled and seem to have a different surface structure: could be tortoise, indeed.

Most if not all of the mottled look to the carabao horn on the front of the scabbard is delamination (separation of the layers in the horn) that was most likely caused by the heat created when the holes were first drilled into it. If enough heat is generated from the use of dull drilling tools this damage can be seen when first done or not until years later when drying and shrinkage from age can affect the horn and put extra stress on the material at these points. Impact from other objects can cause this as well. JMHO.

Best,
Robert