If earrings have ever left your lobes sore, itchy or weeping, the stone is almost never the cause. It is the post.
Nickel is usually the culprit
Nickel allergy is one of the most common contact allergies there is, and jewellery is where most people meet it. It is used to harden and whiten alloys, which is why it turns up in inexpensive earring posts and findings.
The reaction takes hours to appear, which is why people often blame the wrong pair. Redness, itching and a weeping crust around the piercing are the classic signs.
It is an allergy rather than an irritation, so it does not improve with repeated exposure. It usually gets worse.
Moissanite itself is inert
Worth saying plainly: the stone is not the problem. Moissanite is silicon carbide, chemically stable, and does not react with skin.
The same is true of the stone in any reaction to a diamond, cubic zirconia or crystal earring. Look at the metal.
Which metals are safest
Surgical stainless steel is widely used for piercings and tolerated by most people, though some grades contain small amounts of nickel.
Titanium is the safest common option. It contains no nickel, is very light, and is what piercers generally use for fresh piercings.
Solid gold, 14k or higher is generally well tolerated. Lower karats contain more alloy, which means more chance of nickel.
Sterling silver is usually fine, though some sterling alloys and plating layers include nickel.
Plated metals are the risk. Plating wears through at exactly the point that sits in the piercing, exposing whatever is underneath.
It is not always an allergy
Several other things produce similar symptoms and are easier to fix.
Soap and shampoo residue collects behind the earring and stays against the skin. Rinsing thoroughly in the shower helps more than people expect.
Earrings left in continuously never give the piercing a chance to dry out. Taking them out overnight, or alternating pairs, breaks that cycle.
Backs pushed on too tightly compress the lobe and trap moisture against it. The back should sit against the lobe, not squeeze it.
Heavy earrings drag on the piercing and enlarge it over time, which causes soreness that has nothing to do with metal at all.
Keeping them clean
Wash the posts and backs with warm water and mild soap, rinse thoroughly, and dry before wearing. Rinse more than feels necessary, since leftover soap is itself a cause of irritation.
For moissanite, a soft brush on the underside of the stone removes the skin oils and product build-up that dull sparkle.
If a reaction persists
Stop wearing the pair that caused it, and give the piercing time. If it does not settle within a week or two, or if there is spreading redness, heat or discharge, see a pharmacist or doctor rather than trying another pair.
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