I am a metalsmith, so, in the event that you haven't been able to apply the patina yet, I thought I would add another suggestion.
We use liver of sulfur to oxidize silver, then use a brass brush or pumice to remove the oxidation from the surface and leave it in the nooks and crannies.
For the solution to work, either the metal or liver must be heated... The liver is made with water and the sulfur mineral.
I guess this may sound sort of complicated, but if you have no luck, I'm sure a local jeweler would be happy to do this for you, as it would only take a moment.