Now is the time to Polish Your Petoskey Stone

Tracy Stengel
Photo bythe author, Tracy Stengel

While you are dreaming of boating season, sand, and abundant sunshine, bring back fond summer memories by digging out that Petoskey stone you found last year. Now is the time to polish Michigan’s official state stone.

The beloved Petoskey — nothing gets old about this 350-million-year-old fossil.

From Spring to Fall, millions of people come from all over the world to comb the shores of Northern Michigan in hopes of finding a Petoskey stone. Nothing is better than blue, cool, water licking ankles, toes touching sand, a breeze in your face — and then you see it — a rock looking back at you. Children and adults squeal with delight raising their find in the air like a trophy.

But then, you get it home, intending to display your prized find and blink twice. Now it’s dry. What happened? Where did the eyes go? The rock appears ordinary. Plain. Unremarkable. It looks nothing like the brown-eyed beauty you found in the water and far from the shiny, glass-like stunners you saw in the gift shops.

Rest assured, you can make your Petoskey stone look just as beautiful when it is dry as when it is wet. All it takes is time, elbow grease, and a few supplies.

It is important to remember to always work with a wet stone. The dust created by dry sanding can damage your lungs.

If you are starting with a pitted or uneven Petoskey, use a metal file to shape and smooth out the rough patches.

For beginners, I recommend starting with a relatively smooth stone that is “pure Petoskey,” meaning when you wet the stone, you can see the pattern clearly throughout.

Take off any rings so they don’t get scratched. Use an old towel to drape across your lap to protect your clothing. Keep a bucket handy with a few inches of water.

Begin with 220-grit silicon carbide waterproof sandpaper. Hold the rock firmly in one hand and start sanding with the other. Go in a circular motion. If a back-and-forth motion is easier for you, keep turning the stone to avoid creating any grooves. Use your fingers to detect rough spots that may not be visible.

Once the stone feels smooth, let it dry. Inspect it for any scratches or white spots. If you detect any, wet the stone and work on those areas with the 220-grit paper until the stone is free of blemishes when dry. This step will take the longest and is the most important.

Repeat the process with 400 and 600-grit silicon carbide waterproof sandpaper. You can go up incrementally from 800 to 3000-grit paper, but it isn’t necessary. If you are thorough with each step, you can stop after 600-grit and still get that “gift shop gloss.”

Change your water and rinse your stone often. Between each step, remember to dry and inspect your stone. If there is a flaw, do not go to the next grit. Whatever blemish you see on a dry stone that was sanded with 220-grit paper isn’t going to disappear when you move to 400-grit. Being patient with each step will save you time and frustration.

Once you are satisfied with how your dry stone looks after sanding with the highest grit level you are using, at least 600, now it’s time to polish!

I use Zam, a jewelry polish you can find online. It comes in a tube and resembles a very hard, green wax. Chip a few flakes off the top of the tube with the end of a screwdriver or knife and let them fall on a piece of corduroy or velvet. Use a rotating rubbing motion to work the polish compound onto the stone. Wipe with a clean, dry cloth.

Now you should have a beautiful, perfectly polished Petoskey stone you can cherish forever.

If you aren’t happy with your stone after polishing, go back at least to the 400 grit and repeat the process.

Polishing Petoskey stones isn’t a quick process, but nothing good ever comes easy! This pure Michigan pastime, while sometimes tedious, is tremendously rewarding.

If you have any questions, please leave them in the comments!

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Tracy explores the world with a positive eye, an open heart, and a sprinkling of humor. Without laughter, she would be lost.

Onsted, MI

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