Cleaning and prepping specimens without damaging them

Not every specimen can be cleaned the same way, and the wrong method can genuinely damage a piece that survived millions of years intact. Ultrasonic cleaners are excellent for tough, solid material but can crack specimens with internal fractures or fragile inclusions, a real risk with material like emerald or certain fossils. Acid cleaning, sometimes used to remove unwanted matrix from around a specimen, will also dissolve or etch carbonate minerals like calcite regardless of whether that was the intended target, so it should never be used near acid sensitive material. When in doubt about a specific specimen, a soft brush and plain water is the safest starting point, and it is always easier to clean a specimen further later than to undo damage from an overly aggressive method used too early.