The user instructions provided with the Jewel Jet Steamer caution against steam cleaning most gemstones except rubies and diamonds. After some online research I learned that steam cleaning is not recommended for tanzanite, emerald, topaz, etc. You can read more about this at http://www.andrewberry.co.uk/gemstones_care_of.htm. Although the Jewel Jet cleans most diamond and ruby jewelry, you will need use the "soapy water and soft brush" method for everything else. If I had known that steam cleaning was so limited, I would not have purchased the unit. That's probably why there is no warning about steam cleaning jewelry in the product write-up. I should have done my research before ordering.