[A. G. Maisey]

The Jawa wrongko looks like trembalu to me.

I do not know the local and correct name for the wood in the Malay wrongko.

I have seen this degree of chatoyancy in many other woods, both SE Asian woods and European woods. You can find a chatoyant grain such as we see here in any number of common cabinet timbers, walnut for instance. In SE Asian timbers I've seen similar grain in scented sandalwood.

I'm afraid that from a picture of a piece of polished wood I simply cannot tell what the wood might be most of the time. I'm just not that good.

EDIT I probably should add that kemuning is certainly known in Jawa, but we know it as material for jejeran; it is ideal for this purpose because it has a tight, close, fine grain.Its a yellowish wood and needs to be stained after it has been carved. In these wrongkos with highly chatoyant grain, I don't see anything that I would recognise as kemuning.