The Dos & Don'ts of Ultrasonic Cleaners

An ultrasonic cleaner is a device that uses ultrasound to remove the dirt from your jewelry. The items are placed in a tank filled with a cleaning solution, and after the cleaner is turned on, its motor produces ultrasonic vibrations through the liquid. These vibrations break down the dirt and grime that have accumulated on the surface of your jewelry. Ultrasonic cleaners are great for cleaning the parts of your jewelry that are otherwise unreachable when using more conventional methods.

They do, however, come with a word of caution as they are not safe for all gems and jewelry. Here are the Gemological Institute of America's (GIA) "dos and don'ts" for ultrasonic cleaners:

  • Don’t use an ultrasonic to clean gemstones that have surface reaching breaks that have been filled. Diamonds, for example, can be fracture filled with a lead glass-like substance. Emeralds’ fractures are commonly filled with oil, resin or wax. The goal of these treatments is to improve apparent clarity. However, these types of treatment are not permanent and can be damaged or removed. Other gemstones may be similarly treated.
  • Don’t use an ultrasonic to clean organic gem materials. These are porous materials and should never be cleaned using an ultrasonic machine because they can be damaged by the heat of an ultrasonic cleaner and the chemicals in most cleaning solutions. Pearls,coral, tortoise shell, ivory, shell cameos, jet, and amber should not be put in an ultrasonic cleaner.
  • Don’t use an ultrasonic machine if the gems have been impregnated or coated with oil, plastic or wax. These treatments are often used on gems such as emerald, lapis lazuli, malachite, and opal.
  • Avoid ultrasonic cleaners if the gem has been treated by heat, a method used to enhance color.While transparent ruby and sapphire require caution, star ruby and star sapphire should not be cleaned in an ultrasonic machine.
  • There are many gems that are susceptible to heat and temperature changes and should not be cleaned in an ultrasonic regardless of whether they are treated or untreated. Some of these gems include tanzanite , feldspar (sunstone  and moonstone), fluorite, iolite, kunzite, lapis lazuli, malachite, opal, topaz, turquoise, zircon, and others.
  • Use gentle cleaning solutions, such as Touch of Purple, that are specially formulated for cleaning delicate gems and metals that are oxidized or antique. Standard cleaning solutions can damage delicate gem materials and surface finishes.
  • Check to make sure the gemstones in your piece are securely set in their mountings both before and after cleaning. The vibration generated by an ultrasonic cleaner can sometimes shake gems loose or cause damage if gems are set with their girdles touching.

With all these warnings, you may wonder why you would even use an ultrasonic cleaner in the first place. Ultrasonics can effectively clean those hard to reach places, but just use caution as the GIA does recommend, "If you're uncertain about the durability of your gem, avoid using ultrasonic cleaners to be safe."

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