Silver tarnishes after exposure to contaminants such as ozone. The best way to deal with this is use silver dip or wipe with a polishing cloth.
Argentium sterling silver – is also a silver alloy like sterling silver. Argentium sterling silver is at least 92.5% silver and a combination of copper and germanium, Argentium sterling silver does not tarnish.
The primary use of gold / palladium alloys is in jewellery. The alloy is more commonly known as white gold and is an alternative to platinum. Gold / nickel alloys are also used as white gold. In both cases some other metals may be present in small amounts such as silver, zinc and copper.
The cost of palladium white golds are greater then that for nickel white golds due to palladium higher cost and more difficult processing. Palladium white golds are also softer and more ductile compared to nickel white golds. In both cases it is not possible to have white gold with a purity greater than 21 carat.
There is a risk of allergic reactions with sterling silver too.
Another option is to avoid base-metal alloys entirely, and instead use elemental and precious metals in your custom jewelry. The following options are all nickel free.
Sterling silver is an alloy, but does not contain any nickel, so is wearable by most segments of the population. Sterling is sometimes stamped .925, because it’s made of at least 92.5% pure silver. Typically the remaining 7.5% consists of copper.
Tarnish-resistant Argentium sterling silver is 1.2% germanium, 6.3% copper and 92.5% silver.
Niobium is an element and is therefore not mixed with any other metals. It is naturally nickel free and very resistant to corrosion. Niobium comes in a wide variety of anodized (non-plated) colors.
Titanium is also an element and thus naturally nickel free. Like niobium, it’s highly resistant to corrosion. Because of this, titanium is frequently used in medical implants and is a good choice for earring findings.
14k White Gold is commonly made of the following materials: 58% pure gold, 25% pure silver, and 17% pure copper. Gold can be alloyed with other metals, too. Be aware that white gold commonly contains nickel (added for both color and strength).
The term hypoallergenic was made up in the 1950’s as part of an advertising campaign and has since been adopted to indicate that the metal used has a diminished potential for causing an allergic reaction.
Tarnishing – Some, not all, metals tarnish. The discoloration occurs when the metal is able to react with or be attacked by something that can make a chemical compound with the underlying metal. Silver can react with oxygen or sulphur compounds to form a brownish-to-black tarnish film. This is due to the formation of oxides (An oxide is a chemical compound containing at least one oxygen atom as well as at least one other element) and/or sulphides (a compound of sulphur and an element that has a more positive electric charge) on the metal surface. Because of the small particle size, the oxide/sulphide particles on the surface appear black, so the metal loses its luster. Pure gold is resistant to such reactions however lower karat golds are all alloys of gold with other metals and as such can tarnish. Wherever it occurs, tarnish almost always looks very different from the original polished metal. Tarnish is removed either by employing another chemical reaction to dissolve the tarnished surface or by using a mild abrasive to actually polish away the discolored compound on the metal to expose the underlying metal again. Ordinarily, such cleaning processes remove very little of the original metal.
Metal hardness – Titanium is given a 6 on the Mohs Hardness Scale, a scale used to rank materials by their scratch resistance. In comparison, gold is a 3 rating, and platinum is generally given a rating of 4 to 4.5. So, titanium rings are a few times harder than their precious metal counterparts.