[David]

Originally Posted by Gonzoadler

Concerning the hilt cup and ring:
The cup could also be a copper alloy, at one point it shines golden through the dark surface. But maybe it is silver, I'm just not sure.
I added two pictures of the ring.
Yes, David, you are right, there are real stones in the ring. It's no glass, because they have a lot inclusions. The ring itself shines golden and had no patina as I got the Keris some years ago. Because of that I suspect the material is this indonesian gold alloy, called suwasa. But maybe it is just brass.

It seems to be right that the Keris is incorrectly mounted. But the hilt stucks and I wouldn't like to damage anything.

Hi Robin. Thanks for the additional photos. They don't help too much since they aren't really in focus, but i don't think anyone could tell you definitively whether those are yakut (quartz) or inten (low grade diamond) even if the images are sharp. Suassa could well be the material they are mounted in, and your most recent images do hint at that. If this were mine i would take it to your local jeweler and see what they have to say. I bought a keris into a jeweler once to ID some stones and they actually got a real kick out of it. Didn't even charge me for the assessment. They could also tell you if the metal has any gold content. It may not really matter to you now, but you would definitely assign different levels of value to this keris dependent upon which materials are actually used here, so it my be something you would want to know down the line.
There are ways to loosen a fixed hilt, but with a fragile ivory hilt that already shows some age cracks i fully understand why you might simply accept the upside down fitting rather than risk damaging the ivory.
I did note one additional question that was not fully addressed.
"And has the fine carved hilt a religious or mythological meaning?"
As Jean mentioned this hilt form is known as Jawa Demam, which translates to something like "Feverish Javanese". This is due to the bend over posture of the abstract figure with one arm across its belly as if in some pain or distress. I don't know exactly when this name was first applied to this hilt form or even if this idea was the original intent of those who designed it. But from what is known i don't think there is a particular religious element to it. The reasoning for the naming, beyond the obvious body position, seems to have been lost to time. There are many variations on the Jawa Demam hilt. This particular form and motif design is specific to Palembang though and a lovely example of the form.
All-in-all this is a lovely keris. If you were only to have one in your collection this is not too shabby.