Best etchant for gold and silver mokume?

Hi all–I recently purchased a piece of 14K palladium white
gold/sterling silver mokume sheet from Reactive Metals (great folks,
BTW).

To those who have worked with gold/silver mokume–which would be a
better etchant for this material: ferric nitrate or nitric acid? I
can work with either safely, so my primary concern is getting a
nice-looking etch.

Many thanks for any suggestions!

Dorian