Hi all,
I was asked to post this chart on which stones can and cannot be
cleaned in an ultrasonic cleaner.
I found the chart below years ago and I’d gladly credit the author
but no name is listed. 
Generally speaking, organic materials (bone, coral, pearls, etc.)
cannot take ultrasonic cleaning. Yes, that also means you should
not be sticking your hands into an ultrasonic cleaner while it’s
running. But there are other materials that don’t take ultrasonic
cleaning either. The chart below should help.
This chart is a few years old so feel free to post your comments or
additional recommendations.
If you are going to MJSA in New York City, please stop by the
Gesswein booth. I love to meet Orchid members! 
Best Regards,
Elaine Corwin
VP Tech Services
Gesswein Co. Inc. USA
Tel: 1-800-544-2043 x 287
Recommendations for Cleaning of Various Stones:
AMBER
Ultrasonic: No
Steam: No
Boiling: No
Comments: Wipe with soft cloth. If further cleaning is needed, use warm
water, mild detergent, rinse and dry thoroughly.
AMETHYST
Ultrasonic: OK
Steam: Gently
Boiling: No
Comments: Generally poses no particular cleaning problem.
AQUA
Ultrasonic: OK
Steam: Gently
Boiling: No
Comments: General poses no particular cleaning problem.
CARNELIAN
Ultrasonic: No
Steam: Gently
Boiling: No
Comments: Wipe with soft cloth. If further cleaning is needed, use warm
water, mild detergent, rinse and dry thoroughly.
CITRINE
Ultrasonic: OK
Steam: Gently
Boiling: No
Comments: Generally poses no particular cleaning problem.
CORAL
Ultrasonic: Best avoided
Steam: Best avoided
Boiling: No
Comments: Warm, mild soapy solution and soft brush, safest method.
DIAMOND
Ultrasonic: OK
Steam: OK
Boiling: OK
Comments: Generally poses no particular cleaning problem.
EMERALD
Ultrasonic: No
Steam: No
Boiling: No
Comments: Warm, mild soapy solution and soft brush
GARNET
Ultrasonic: OK
Steam: Gently
Boiling: No
Comments: Generally poses no particular cleaning problem.
HELIODOR
Ultrasonic: OK
Steam: Gently
Boiling: No
Comments: Generally poses no particular cleaning problem.
JADE
Ultrasonic: OK
Steam: Gently
Boiling: No
Comments: Wipe with soft cloth. If further cleaning is needed, use warm
water, mild detergent, rinse and dry thoroughly.
KUNZITE
Ultrasonic: No
Steam: Best avoided
Boiling: No
Comments: Fragile stone; warm, mild soapy solution and soft brush, safest
method.
LAPIS
Ultrasonic: Best avoided
Steam: Gently
Boiling: No
Comments: Be careful; material varies greatly; warm, mild soapy solution and
soft brush, safest method.
OPAL
Ultrasonic: No
Steam: No
Boiling: No
Comments: Fragile stone; warm, mild soapy solution, safest method.
PEARLS
Ultrasonic: No
Steam: No
Boiling: No
Comments: Wipe with soft cloth. If very stained, warm, mild soapy solution on
rag; don’t dip in liquid. Be careful to dry thoroughly. Moisture remaining in
drill hole can eventually cause discoloration.
PERIDOT
Ultrasonic: OK if cool
Steam: No
Boiling: No
Comments: Fragile stone; warm, mild soapy solution and soft brush, safest
method.
RUBY
Ultrasonic: OK
Steam: OK
Boiling: Best avoided.
Comments: Generally poses no particular cleaning problem.
SAPPHIRE
Ultrasonic: OK
Steam: OK
Boiling: Best avoided.
Comments: Generally poses no particular cleaning problem.
SPINEL
Ultrasonic: OK
Steam: OK
Boiling: No
Comments: Generally poses no particular cleaning problem.
TANZANITE
Ultrasonic: No
Steam: No
Boiling: No
Comments: Fragile stone; warm mild soapy solution and soft brush, safest
method.
TOPAZ
Ultrasonic: Best avoided
Steam: Gently
Boiling: No
Comments: Material has easy cleavage; if visible keep out of ultrasonic.
TOURMALINE
Ultrasonic: OK
Steam: Gently
Boiling: No
Comments: Generally poses no particular cleaning problem.
ZIRCON
Ultrasonic: OK
Steam: Gently
Boiling: No
Comments: Generally poses no particular cleaning problem.