These five metals are used untreated, allowing their nature to shine true. I use all of these especially in my more simple pieces, such as unisex chains and bracelets.
Aluminium is a fairly common material for costume chainmail (meaning one you wear to look good, not defend yourself from swords, or dragons for that matter). Some aluminium used in chainmail will produce a black layer of oxide over time. The aluminium I use for my jewelry does not.
Note: When using aluminium, one should always ensure that the temper is suitable to the application. Dead soft aluminium has been sold in kits for armor... If you can bend a rings with your finger, don't use it for armor. Such rings are useful to create ring sculptures. If you are trying to make an armor (standard european 4 in 1), I suggest 14 gauge rings made on a mandrel with a 3/8 of an inch diameter. This makes it fairly quick to do. It is not the tightest weave : I used a 16 gauge, 1/4" diameter interior diameter for a much denser weave, which has a nice look but it really longer to make.
A strong metal, I use it to create jewelry with an authentic medieval/historic feel. Brass oxidize slightly over time, but since the rings I use are solid brass, the pieces can be cleaned to bring out the original shine. Brass can be soldered and worked using traditional jewelry methods, allowing for some interesting possibilities in chainmail by incorporating worked rings into pieces.
A strong metal, it is often used as trimming in chainmail armors. Bronze turns darker with time. Like brass, I like to use bronze for an authentic feel. Fairly heavy. Bronze can be soldered, creating a whole range of possibilities.
Sterling silver is a precious metal. Shiny and beautiful, it can be soldered, which gives a whole range of possibilities. However, it price is very high. Since most chainmail jewelry requires quite a lot of metal, I rarely use this, except upon request. Silver also has the tendency to darken with time (by taking up sulfur from the air and materials in contact with it), necessitating more care than aluminium.
Stainless steel/ Surgical steel
I used stainless steel mostly for extension chains and men jewelry. Stainless steel, is, well, stainless, so it won't rust. And it's very strong. It is not as shiny as aluminium, and is slightly darker too. Obviously, steel is a great choice for armor or pieces intended to secure loads. It is however much harder to work with. I recommend using very good pliers and not working for too long if you make a project using a lot of steel rings, as the repetitive motion used to weave chainmail could lead to injury.
I also use surgical steel findings. For the moment, these must be requested. I plan to have switch entirely to these findings (except for copper coloured earrings).
Quick comparison of shine and color
You can compare the shine and color of each of the white metals described here. From left to right : sterling silver, aluminium, stainless steel, silver anodized aluminium. Sterling silver is whiter than aluminium, but slightly less shiny. Steel is duller and grayer than both of them. The silver anodized aluminium is both very white and very shiny. Steel and silver add weight to a piece, which might be good or not, depending its use and function.