Seerp, if you have a look at Edward Frey:- "The Kris" Oxford University Press you will find a couple photos of the remnant of the meteorite, and a short commentary on it. I cannot find my copy of Frey at the moment. Sorry.
I visit the public areas of the Keraton Surakarta Hadiningrat regularly, my most recent visit was in April this year, but I've only seen the meterorite remnant once, and that was perhaps 25 years ago. Even if you could see it in person, I doubt that you would learn anything from it. There's not much of it left, from memory, its about 24 inches long, 18 inches high, less than 18 inches wide.
It fell near Prambanan in about 1740, and broke into two large pieces and an uncounted number of smaller pieces. The people around Prambanan had been finding and selling the little pieces as talismans from the time of its fall. There was no problem at all in finding the meteorite, the locals saw and heard its fall, apparently it put on quite a show.
The first large piece was taken to Surakarta in 1784, the second large piece was taken in 1797. The palace empus had started to play with the stuff by about 1820.
In theory, pieces of the meteorite were only made available to the palace empus for use for select people, however, being Jawa it was apparently not too difficult to obtain a piece for use in one's own keris, if one had the means to pay for it.
In respect of Keraton "policy" for gifting of pieces of the meteorite, I know nothing, but again, this being Jawa, the Keraton being central to Jawa, and Sinuhun being central to the Keraton, my guess is that gifts would have been made on feeling at the time, not on any set policy.
All the above is written from memory, and I will stand correction on any part of it.
Edit:- I did a google on this, seems there are more than a few entries, somebody with time to spare might be able to dredge up a bit, here is a link to one that I looked at, seems like useable info:-
http://evols.library.manoa.hawaii.ed...pdf?sequence=2