How do I clean an engagement ring with an ultrasonic cleaner?

An ultrasonic cleaner will strip grime off a diamond engagement ring faster than anything else I keep at the bench. I still don't reach for it first. Most engagement rings can handle it, but the exceptions are expensive ones, and you need to know which yours is before you drop it in.

The machine works by sending high-frequency sound waves through water. That creates millions of tiny bubbles that collapse and blast debris off the metal and stone. It's not scrubbing. It's cavitation. For a diamond set in solid 14k or 18k gold or platinum, it's safe and fast, and it works better than any brush I have at the bench, but only when the stone is intact and the prongs are tight.

What can go in the tank

Diamonds, sapphires, rubies, moissanite, and most lab-grown diamonds can go in, as long as the stone isn't heavily included or fracture-filled. If your diamond report says clarity-enhanced or fracture-filled, skip the tank. The filler can cloud or wash out.

What shouldn't go in

Skip the machine entirely for emeralds, opals, pearls, turquoise, coral, lapis, amber, jade, and any stone with an oil or resin treatment. Emeralds are routinely oiled to fill surface-reaching fissures. The ultrasonic will pull that oil out in one cycle and leave the stone looking tired. Pearls and opals can crack from the vibration or the heat. If you don't know whether your stone is treated, clean it with a soft brush and warm soapy water instead.

Also skip it for any ring with a loose or missing prong, a chipped girdle, or pavé that hasn't been checked in years. The machine won't loosen a properly tightened prong, but it will absolutely shake a loose one free. Last spring a client named Daniel cleaned his fiancée's ring in a $40 ultrasonic before proposing. A pavé diamond came loose. We found it in the bottom of the tank, which is the best outcome. Sometimes they go down the drain.

Step-by-step, the way I do it

You don't need the heavy-duty tank I use at the bench. A $40 to $60 stainless model with a basket is enough for one ring.

1. Fill the tank to the line with warm tap water, not boiling. Hot enough to be comfortable, not hot enough to steam.
2. Add a small squirt of ammonia-free dish soap. Blue Dawn is what I keep in the studio.
3. Place the ring in the basket, not directly on the tank floor. The buzzer has to reach all sides.
4. Run the machine for 2 to 3 minutes. If the ring hasn't been cleaned in a year, run it 5, but not longer.
5. Rinse under warm running water with the drain closed or a strainer in the sink. This is non-negotiable.
6. Pat dry with a lint-free cloth and let it sit for 10 minutes before putting it back on. A microfiber lens cloth works.

If the water comes out gray and the diamond looks flat afterward, run another short cycle. Sometimes one pass isn't enough for years of hand cream and hair product.

How often to clean it

Once a month is plenty for most rings worn daily. More than that and you're not cleaning the ring, you're just running it through a machine. If you wear your ring to the gym, cook with it, garden with it, clean it when it looks dull. The ultrasonic is excellent, but it doesn't replace checking prongs. That's still a twice-a-year job for a jeweler with a loupe.

One more thing. If your white gold ring hasn't been rhodium-plated in years, the ultrasonic won't hurt it, but it will take off every bit of hand cream hiding the warm tint underneath. You might think the machine ruined your ring. It didn't. It just showed you what was already there.

And if the stone is an emerald or an opal, keep it out of the machine no matter what the listing promises. I've seen what an ultrasonic does to an oiled emerald.