I'm hearing that aluminum is a good metal for jewelry chain. What are the benefits to using aluminum vs. sterling silver? Also, what is rhodium? Is it hypoallergenic? Thank you.
Aluminum is a very soft lightweight metal that does not rust. It is an affordable alternative to precious metals. Aluminum must be anodized to keep it from tarnishing which makes it even less likely to cause skin irritation--which is a great benefit.
Sterling silver items are made of 92.5% pure silver and 7.5% copper or other alloy--proportions fixed by law. Allergic reactions to sterling silver are usually caused by the metals used in the alloy rather than the silver itself. Sterling silver will "patina" in time, that is, its color will take on an "antique" look. It is more durable and harder than aluminum and in general will create a longer lasting finished product than the aluminum.
Nickel is a highly durable metal that is often used as an alloy with other metals. It is most often the metal in jewelry which causes skin irritation. It depends on how sensitive people are to nickel as to which metals they can wear. The higher the karat gold or percentage of silver in metal the less of other metals are added, making them more hypoallergenic.
Rhodium is a hard silvery white metal that is highly reflective, which makes it ideal to use for plating on other alloy metals. Rhodium, like gold is a pure metal, and like gold it does not tarnish or oxidize. And yes, it is considered hypoallergenic.
Titanium, Niobium and stainless steel are some of the most hypoallergenic metals.