Wondering if it is okay to clean that gemstone or piece of jewelry in your ultrasonic cleaner or using steam? What is the best way to clean a particular gem? The method depends on the gem's toughness and characteristics. Using the wrong method could result in the destruction of the stone.

Laboratory grown synthetic gemstones have essentially the same appearance and optical, physical, and chemical properties as the natural material that they represent.¹ There are a few exceptions like synthetic opals which are  harder than their natural versions because they contain no water and synthetic amethyst which cannot be cleaned ultrasonically. Synthetic gemstones produced in the United States include alexandrite, coral, diamond, emerald, garnet, lapis lazuli, quartz, ruby, sapphire, spinel, and turquoise.

In the tables below, if neither method is listed suitable, click the gem name to see suggested alternatives.

Amber: Clean with a mild solution of soapy, slightly warm water, and use a flannel cloth. Don't rub or scrub as this will scratch the Amber. Rinse quickly with clean, cool water. Dry with a soft, clean, absorbent cloth then air dry on a towel until completely dry. For mounted pieces, clean the metal with a soft polishing cloth, avoiding contact with the amber. Avoid heat and chemicals as amber can be partially dissolved by solvents including alcohol. [top]

Aquamarine: Is often heat-treated to remove traces of yellow and to intensify its rich blue color. This can leave it susceptible to damage if cleaned using a steam or ultrasonic cleaner. Clean with a mild solution of soapy, slightly warm water, and use soft brush. Dry with a soft, clean, absorbent cloth then air dry on a towel until completely dry. [top]

Cat's Eye (Chrysoberyl): Clean with a mild solution of soapy, slightly warm water, and a soft brush. Rinse quickly with clean, warm water, dry with a soft, clean, absorbent cloth then air dry on a towel until completely dry. [top]

Coral: Wipe gently with a damp cloth that is soft and clean then dry with a soft, clean, absorbent cloth. Place on a towel to air and ensure complete dryness. If mounted, clean metal with a soft polishing cloth, avoiding contact with the coral. Do not expose to cleaning agents or chemicals. [top]

Emerald: Many emeralds have natural fissures or inclusions and even lab grown emeralds can have inclusions and veils. Often they are treated with colorless oils or resins to improve the emerald's clarity and color. You can use a mild jewelry cleaning solution, (or make you own solution by combining cool water and mild dishwashing liquid: 2 tablespoons of dishwashing liquid to 1 quart of water). Soak no more than 5 minutes, rinse with clean, cool water then dry thoroughly with a soft, dry, and clean cloth. Place on a towel to air and ensure complete dryness. Avoid scrubbing. [top]

Iolite: You can use a mild jewelry cleaning solution, (or make you own solution by combining cool water and mild dishwashing liquid: 2 tablespoons of dishwashing liquid to 1 quart of water). Soak no more than 5 minutes then gently, brush the top, sides and underside with a soft brush to remove the softened residue. Rinse with clean, cool water then dry thoroughly with a soft, dry, and clean cloth. Place on a towel to air and ensure complete dryness.  [top]

Jade: Jade is often treated by dyeing, waxing, or bleaching to improve its color and appearance. Wipe gently with a damp, soft clean cloth to clean then dry with a soft, clean, absorbent cloth. Air dry on a towel to ensure complete dryness. Do not expose to cleaning agents or other chemicals. [top]

Lapis Lazuli: Splash sparingly with a mixture of mild liquid soap and cool water (1 teaspoon of soap to 1 cup water). Rinse quickly with clean, cool water then dry with a soft, clean, absorbent cloth. Air dry on a towel to ensure complete dryness. [top]

Marcasite: Because marcasite is often secured in a setting with jeweler's cement it make it risky to clean using steam or ultrasonic cleaners. Wipe gently with a damp cloth that is soft and clean then dry with a soft, clean, absorbent cloth. Air dry on a towel to ensure complete dryness. [top]

Onyx (Calcedony): Almost always dyed to produce a range of colors. Avoided contact with chemicals. Clean with a mild solution of soapy, slightly warm water, and a soft brush. Rinse quickly with clean, warm water, dry with a soft, clean, absorbent cloth then air dry on a towel until completely dry. [top]

Opal:Opals are delicate due to their softness (5.5-6.5 Mohs) and their water content. Generally they do not need any special care while stored unless they are in a very dry climate or dehumidified room, then storing them in a tight plastic bag with a damp piece of cotton or fabric will prevent dehydration. Their water content makes them susceptible to cracking if subjected to quick and extreme temperature changes. Their softness make them prone to scratching easily and simply wiping dust off will reduce it's polish. Clean using a soft cloth or brush, a mild detergent, and room temperature water then rinse to remove any residue. Avoid soaking opal doublets or triplets since this may dissolve the glue holding the layers together. If at all possible, have opals cleaned by a professional jeweler. [top]

Pearl, Mother of Pearl, Nacre:  After wearing, it is wise to wipe pearl jewelry gently with a damp cloth that is soft and clean in order to remove any perspiration, oil, residue or chemicals that may have come from the skin or it may have been exposed to. Wipe gently with a damp cloth that is soft and clean. If you use a cleaning agent, use one that is specifically made for pearl products. Dry with a soft, clean, absorbent cloth then air dry on a towel to ensure complete dryness. Do not expose to hairspray or any other chemicals used to clean or for personal hygiene. [top]

Peridot: A fragile stone that can be damaged over long periods of time by exposure to various chemicals, and even by perspiration. Sudden temperature changes can also cause Peridot to fracture. Clean using a soft cloth, a mild detergent, and warm water, rinse to remove any residue, air dry on a towel to ensure complete dryness. [top]

Tanzanite: Is often heat-treated to produce a range of colors, is very fragile and sudden exposure to extreme temperature changes can cause it to fracture. You can use a mild jewelry cleaning solution, (or make you own solution by combining cool water and mild dishwashing liquid: 2 tablespoons of dishwashing liquid to 1 quart of water). Soak no more than 5 minutes then gently, brush the top, sides and underside with a soft brush to remove the softened residue. Rinse with clean, cool water then dry thoroughly with a soft, dry, and clean cloth. Place on a towel to air and ensure complete dryness. [top]

Topaz: Commonly treated with heat and/or irradiation to enhance or change its natural color. Exposure to high heat or sudden temperature changes can cause fractures or a loss of color.  Clean using a soft cloth, a mild detergent, and warm water, rinse to remove any residue, air dry on a towel to ensure complete dryness. [top]

Tourmaline: You can use a mild jewelry cleaning solution, (or make you own solution by combining cool water and mild dishwashing liquid: 2 tablespoons of dishwashing liquid to 1 quart of water). Soak no more than 5 minutes then gently, brush the top, sides and underside with a soft brush to remove the softened residue. Rinse with clean, cool water then dry thoroughly with a soft, dry, and clean cloth. Place on a towel to air and ensure complete dryness. [top]

Turquoise: Is often sealed with an acrylic resin to enhance its color, texture, and hardness. Wipe gently with a damp cloth that is soft and clean then dry with a soft, clean, absorbent cloth. Air dry on a towel to ensure complete dryness. Do not soak in water and do not expose to cleaning agents or other chemicals. [top]

Tanzanite: You can use a mild jewelry cleaning solution, (or make you own solution by combining cool water and mild dishwashing liquid: 2 tablespoons of dishwashing liquid to 1 quart of water). Soak no more than 5 minutes then gently, brush the top, sides and underside with a soft brush to remove the softened residue. Rinse with clean, cool water then dry thoroughly with a soft, dry, and clean cloth. Place on a towel to air and ensure complete dryness. [top]

Zircon: You can use a mild jewelry cleaning solution, (or make you own solution by combining cool water and mild dishwashing liquid: 2 tablespoons of dishwashing liquid to 1 quart of water). Soak no more than 5 minutes then gently, brush the top, sides and underside with a soft brush to remove the softened residue. Rinse with clean, cool water then dry thoroughly with a soft, dry, and clean cloth. Place on a towel to air and ensure complete dryness. [top]

¹ More on how lab-grown gems are made at http://minerals.usgs.gov/minerals/pubs/commodity/gemstones/sp14-95/synthetic.html and http://www.valuablestones.com/synthetic_gemstones.htm