Thank you for your responses
It seems to be one of the prestige objects of this collection, which claims to be one of the most important ones of Javanese gold. Maybe somebody of members has the catalogue:
http://www.yalebooks.co.uk/display.asp?K=9780300169102?
I hope the description would say something more about it.
About the date: I don't understand, how it is possible to put this object in such a fictional time span (which actually has not so much to do with the time span of existing of Mojopahit). One must conclude, there were no developments and changes in art in this time, which were absolutely incorrect.
For an object with such construction the state of preservation seems to be near to pristine. Is it possible, even if this object would come from 1500-1600?
Taking a look at the adornments with stones, I cannot believe, there would not be some kind of restoration or additions made, if this object would have such age indeed.