The entire hand-polishing process can take hours, depending on how fine a result you want. But there are other ways to polish Petoskey stones. Rock tumblers, which have a rotating drum into which you place stones, water, and polishing grit, can yield specimens that are nicely polished on all sides, but they can take around a week and using them can be messy. In addition, tumblers also remove a lot of material from each specimen, resulting in smaller stones. But they are affordable and automated, requiring only periodic maintenance throughout the process. Other motorized equipment, such as wheel-based diamond gemstone polishers, can make the process much faster but require considerable investment and expertise. If polishing your finds yourself isn’t an option, local lapidary professionals or hobbyists could do the work for you. Local rock clubs or online groups can put you in touch with someone willing to work with you. Whatever method you use to polish Petoskey stones, patience is key; even though the stone is soft and easy to work with, it’s easy to scratch, break, or grind away completely.
Some collectors avoid polishing altogether but still achieve that “wet” look by coating specimens in a clear coating of some sort, typically an epoxy or resin. These thick, clear fluids can be used to coat a stone and, once dried, form a permanent coating that can give specimens a richer, more contrasting, “always wet” appearance. However, as limestone is porous and soft, results can be mixed, and this method of treatment should only be used by experienced hobbyists.
This rough piece of Petoskey stone has been coated in a light silicone spray, enhancing its contrast slightly without excess mess.
Petoskey stone is frequently used in jewelry and stone carvings, thanks to its interesting patterns and how easy it is to work with. Knowledgeable lapidaries can cut Petoskey stone at specific angles to achieve the pattern of their choosing or to accentuate features of a specimen. All manner of Petoskey stone jewelry and other wearables and trinkets are abundant and widely available, especially in the Petoskey area.
Petoskey in Aquariums
Some aquarium hobbyists may be tempted to put Petoskey stones or other fossil corals in their fish tanks. This may be fine in the short term, but it could be problematic in the long term. Because limestone consists of calcite, it dissolves easily. As a fish tank’s water becomes less fresh, accumulating waste and other organic by-products, the water can become more acidic, thereby dissolving the limestone. The process may be slow, especially if the fish tank is well-kept, but eventual erosion of the specimen will likely occur. More importantly, this can change the pH balance of the water, which can be harmful to fish.
Specimens courtesy of Bob Wright
These lightly polished Petoskey stone beads are some popular ways to wear the stone while retaining its more natural appearance.