How to Clean a Herkimer Diamond

Telling a Herkimer diamond from ordinary quartz can be a rocky process.
••• quartz sur fond jaune pastel image by Unclesam from

Herkimer diamonds are actually rare crystals found only in Herkimer County, New York. The stones are double-terminated quartz crystals that are diamond-shaped and have a total of 18 facets across the upper, middle and lower sections of each stone. Herkimer diamonds are very clear and bright and cost much more than other crystals, despite the fact that they are rock crystal quartz. There are a few ways to clean a Herkimer diamond properly, but always start by brushing the dirt off the rock with a stiff-bristled brush.

Dishwashing Detergent

    Place the Herkimer diamond in a mixture of 2 cups warm water and a few drops of dishwashing detergent.

    Soak the stone for at least 15 minutes.

    Remove the stone from the dishwashing solution and use the brush to scrub the stone gently.

    Rinse with cool water.

    Polish your Herkimer diamond with a soft, dry cloth.

Hydrochloric Acid

    Soak the stone in hydrochloric acid if it has a white crust. You can find hydrochloric acid in most drug stores and hardware stores.

    Soak the stone until the hydrochloric acid stops bubbling.

    Rinse with cool water.

    Polish the rock with a soft, dry cloth.

Oxalic Acid

    Soak the stone in a mixture of 1 part oxalic acid to 2 parts water, if there is a rust-colored or yellow-colored crust on the stone. You can find this product in hardware stores or online. Oxalic acid is highly corrosive, so use it in a well-ventilated area and keep it away from children and pets.

    Wash the stone with the dishwashing solution.

    Rinse with cool water.

    Polish the rock with a soft, dry cloth.

    Things You'll Need

    • Small, stiff brush
    • Measuring cup
    • Water
    • Dishwashing detergent
    • Hydrochloric acid
    • Oxalic acid
    • Soft cloth(s)


    • Hydrochloric and/or oxalic acid are both potentially dangerous; handle them with caution. Wear protective clothing, gloves and eyewear.

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