Donny, the reason that Balinese blades often appear to be darker than Javanese and other blades is because Balinese blades do not have a textured surface.
The factors that I have listed do cover the reasons for blade colour.
Here is a link to a blade that I made some years ago.
http://www.kerisattosanaji.com/PBXIImaisey2.html
It is a Javanese form, but a Balinese finish. If I had done a textured finish to the surface of this blade it would not appear so dark. However, some Javanese blades even with a textured surface can be pretty dark, its all about the factors that I've listed. Use the "INDEX" tab on the linked page and and you can see recent blades made by other craftsmen working in Surakarta 20 years ago:- some are very black, others are not.
One thing is true:- you cannot alter the colour of the material with which a blade is made. Most older blades are simply impossible to get really black. Really old blades often have pamor that provides contrast by use of high phosphorus and low phosphorus irons, and all you ever get there is dark grey and light grey.
Moderators:- my apologies for the linked pages, but I do not have these photos on file any longer, and I'm not going to photograph them again.