Metals--Aluminum and?

For this particular piece the value is in the design whether or
not precious metals are used...  I am wanting to find a combination
of two differently coloured metals to use for the piece.  A high
priority is tarnish resistance. 

As I’ve mentioned in previous discussions regarding tarnish and base
metals, I get good results with brass and copper using a patina
solution containing selenous acid (e.g., Jax-Black). I rub off the
excess with damp pumice. At least with my skin, I no longer get
any green patches. Brass and copper produce a very nice color
contrast, especially when they do not have a mirror finish and the
recesses of the design are shadowy from the patina.

Judy Bjorkman

The real expert on aluminum in jewelry is Jane Adam in the UK.
Search her name in google to see examples of her work in anodized
aluminum. I thought she did her own anodizing but she apparently
works with preanodized material. For anodizing the best site (
my opinion) to look at is:

http://www.focuser.com/atm/anodize/anodize99.html

also see:

http://www.eastwestdye.com

jesse