[A. G. Maisey]

Sid, you have asked 8 questions, I will address these questions one by one

1) Is this keris 30 years old?
I do not know, see post #3

2) Is this keris part of the batch you refer to?
I do not know, see post #3

3) Did that maker couple a smooth ganja with a rough textured Javanese type blade to add interest?
I would guess that there was more than a single maker involved in the production of what we can see in your photos. There are a number of reasons why the gonjo has been replaced and it is impossible for me make a reasonable guess on why it has been replaced. See post #3.

4) Why not add a scabbard to add value?
We do not know the history of this keris, I think it would have had a scabbard at one time.

5) Why are there not more of these recent types not seen in the meaketplace?
Because not many more, if any more were made.

6) After 30 odd years one could reasonably expect this.
Not necessarily; we are dealing with a niche market and an ethnographic artefact that in its cultural context has quite specific parameters within which to function. We do not know who it was made for, nor why it was made, we do not know if it is something that was produced to function within a cultural context or if it was produced to function within a context other than its designated cultural context. See post #3.

7) Or is this on the balance of probabilities exactly what it is stated as namely a 19th century antique with unique features?
In my opinion it is not a 19th century antique. The body of the blade (wilahan) might have some age, or it might not, I cannot give a supportable opinion on the basis of a photo. The gonjo is very likely to be much more recent than the wilahan. See post #3

8) What is more likely on the facts?
What facts Sid? I cannot see any facts that I could take into even a lower court and expect somebody with no specialist knowledge to agree with. If I were to be granted the status of "expert witness" I could reasonably expect that some people would accept what I have said, and that others would not.

In summary, it is in my opinion impossible to form and support a firm opinion on the age and reason for being of this keris.