Or perhaps, just perhaps, the quoted passage is simply incorrect. That does happen as i am sure you all know. I cannot say that is the case here with any assuredness, however, everything that i have ever read previously about gold, specifically in regards to Javanese culture, falls more in line with what Alan has said. I am away from my reference books at the moment, but i do have one that is specifically related to the use of gold in Javanese culture and i will check in with that when i return. I cannot say, however, that i can recall seeing much of any use of suasa on Javanese keris at all and find the idea that any Javanese Susuhunan or Sultan would prefer suasa to pure gold a bit of a strange one indeed.
