No. Moissanite cannot tarnish, and it is worth understanding why, because the answer tells you what to ask about instead.
Why the stone cannot tarnish
Tarnish is a chemical reaction. It happens when a metal reacts with sulphur compounds in the air and forms a dark film on its surface. Silver does it readily. Copper does it. Brass does it.
Moissanite is not a metal. It is silicon carbide, a compound of silicon and carbon, and it is chemically settled. There is nothing in it for sulphur to react with. It is also unporous, so nothing soaks into it. A moissanite worn every day for ten years is, chemically, the same stone it was on the first day.
The same applies to clouding and yellowing. Those need something to absorb or something to oxidise, and silicon carbide offers neither.
So what does tarnish?
The metal. This is the real question, and it is where most disappointment comes from.
Sterling silver is 92.5% silver and 7.5% other metals, usually copper. That copper is what tarnishes. Unprotected sterling silver will darken over months, faster in humid air or against skin that runs acidic.
Plated finishes behave differently. A gold-tone layer over sterling silver protects the silver underneath while the layer is intact. The question becomes how well the plating holds rather than whether the silver tarnishes.
Stainless steel resists tarnish well but is a different material with a different weight and feel, and it is not what fine jewellery is usually made from.
So when someone asks whether a moissanite necklace tarnishes, they are really asking about the chain and the setting. Ask what the metal is. If the answer is vague, that is itself an answer.
What our pieces are
Every piece we sell is moissanite set in 925 sterling silver beneath a gold-tone finish. Our supplier describes that finish as water-resistant and tarnish-resistant. We pass that on as given rather than as something we have tested ourselves, because we have not.
We would rather tell you that plainly than claim a guarantee we cannot stand behind.
The film that is not tarnish
There is a second thing people mistake for tarnish, and it has a much easier fix.
Hand cream, soap rinsed in a hurry, skin oil, hairspray and perfume build a thin film on a stone. It gathers underneath, which is exactly where light enters. Because moissanite depends on light entering cleanly from below, it shows this sooner than a duller stone would. The piece looks dim and people assume it has gone dull permanently.
It has not. Warm water, a drop of washing up liquid and a soft brush along the underside of the stone restores it in about five minutes. Once a fortnight is plenty.
How to keep the finish
- Wipe with a soft cloth after wearing, and store dry
- Put jewellery on after perfume, hairspray and lotion, not before
- Keep it away from bleach, chlorine, abrasive pastes and ultrasonic cleaners
- Store pieces so they are not rubbing against each other
None of that is about protecting the stone. At 9.25 on the Mohs scale, only diamond and a few laboratory materials can mark moissanite. It is about protecting the metal and the finish, which are the softer parts of any plated piece.
The short version
The stone will not tarnish, will not cloud and will not scratch in normal wear. The metal is where the care goes. Anyone selling you moissanite should be able to tell you exactly what the setting is made of, and what they know about that finish as against what they are repeating.
Our collection is moissanite necklaces and pendants in 925 sterling silver, with complimentary tracked delivery to Canada and the USA.