You’ve probably seen plenty of videos online showing people using ultrasonic cleaners to clean their jewelry. With such a convenient and effective cleaning method, I’m sure you’ve been tempted to try it yourself. However, not all gemstone jewelry is suitable for ultrasonic cleaning. The characteristics of certain gemstones and metals, as well as the way some jewelry is set, may be damaged by the vibrations produced during the ultrasonic cleaning process.
Today, we’ll evaluate this topic from multiple angles—including gemstone hardness, cleavage, structure, setting style…—to help answer the question: Can your gemstone jewelry be cleaned with an ultrasonic cleaner?
How Ultrasonic Cleaning Works?
Before we dive in, let’s briefly look at how ultrasonic cleaners work. These devices use high-frequency sound waves to create tiny bubbles in water. These bubbles rapidly expand and collapse (a process called “cavitation”), and the resulting force can effectively remove dirt, oil, and debris from both the surface of your jewelry and the tiny crevices that are hard to reach with the naked eye.
Factors That Affect Ultrasonic Cleaning of Gemstone Jewelry
1. Gemstone Hardness (Resistance to Damage)
Hardness refers to a gemstone’s resistance to scratches and abrasion. In gemology, we use the Mohs scale to grade hardness, with 10 being the highest. Typically, gemstone hardness is categorized as follows:
- High Hardness (≥7)
- Medium Hardness (5–7)
- Low Hardness (<5)
A higher hardness usually means better durability, which leads many to assume that high-hardness gemstones are always safe to clean in an ultrasonic cleaner. But that’s not necessarily true. While harder gemstones are less prone to surface scratches, hardness doesn’t directly correlate with resistance to breakage.
Ultrasonic cleaners don’t just act on the surface—they also send vibrations through the interior of the gemstone. That’s why, in addition to hardness, we also need to understand toughness—a gemstone’s ability to resist breaking or fracturing. And a gemstone’s toughness is influenced by its cleavage and internal structure. Let’s take a deeper look…
2. Gemstone Cleavage (Tendency to Split Internally)
Cleavage refers to a mineral crystal’s tendency to split along specific crystallographic directions when subjected to external force, forming smooth, flat surfaces. This splitting occurs because the atomic bonds in certain directions within the crystal structure are weaker. You can think of cleavage as an indication of weak planes within the internal structure of a gemstone. Cleavage is typically categorized as follows:
- Perfect Cleavage: The gemstone easily splits along specific directions, forming very smooth, flat surfaces.
- Good Cleavage: The gemstone tends to split along specific directions, forming relatively smooth surfaces.
- Fair Cleavage: The gemstone can split under pressure, but it is less prone to doing so, and the resulting surfaces are less smooth.
- Imperfect Cleavage: The gemstone rarely splits in a specific direction, and when it does, the surfaces are irregular.
- No Cleavage: The gemstone does not split along any specific crystallographic direction. Instead, it breaks irregularly, a phenomenon known as fracture.
The intense force generated during ultrasonic cleaning can be particularly damaging to gemstones with pronounced cleavage. It may worsen existing cracks, create new fractures, or even cause the gemstone to break entirely. Therefore, it is strongly recommended not to use an ultrasonic cleaner on gemstones with perfect or good cleavage. Of course, this should be evaluated along with other factors like hardness and structure.
3. Gemstone Structure (Internal Defects)
Structure refers to the way a gemstone’s internal crystals grow—for example, whether it is porous, layered, etc. The structure reflects the integrity of the gemstone and whether it contains cracks, inclusions, or other internal flaws.
- Porous gemstones are prone to absorbing water during ultrasonic cleaning. Their internal voids may weaken the structure, and after cleaning, evaporation of trapped moisture may cause surface cracking.
- Layered gemstones are vulnerable to peeling or fracturing under high-frequency ultrasonic vibrations.
- Gemstones with visible cracks or fragile inclusions may experience worsened fractures or localized damage when exposed to ultrasonic cleaning.
So, even if a gemstone has high hardness and no cleavage, it may still be unsuitable for ultrasonic cleaning if it has a loose, porous structure or contains numerous cracks or inclusions.
Extra Insight: A gemstone’s structure forms the foundation of its hardness and cleavage—it ultimately influences the gemstone’s physical properties.
4. Gemstone Treatments
While most gemstones retain their natural state from mining to sale, some are enhanced through methods like irradiation, heat treatment, or oiling to improve their appearance. A common example is emeralds, which are often treated with oil to fill their naturally occurring fissures, making them look more refined. Other gemstones may undergo heat or irradiation treatment to enhance their color.
In general, treated gemstones are not recommended for ultrasonic cleaning, as it may damage or reverse the effects of the treatment. When purchasing gemstone jewelry, you can ask the jeweler to provide a gemstone certificate, which usually indicates whether the stone has undergone any treatment.
5. Setting Style and Condition
The way a gemstone is set also plays a critical role in how safe it is to clean with an ultrasonic cleaner. Protective settings like bezel or channel settings help absorb and distribute vibrations, reducing the risk of damage. In contrast, prong settings, which provide less protection, can leave the gemstone more vulnerable to impact.
It’s also important to note that if the jewelry is already loose or damaged, it should not be cleaned in an ultrasonic cleaner, as the vibrations could cause the gemstone to fall out.
6. Metal Type
Jewelry made from common metals like sterling silver, gold (K gold), and platinum is generally safe for ultrasonic cleaning.
Note: Ultrasonic cleaners are not recommended for gold-plated jewelry. The plating layer is extremely thin (usually less than 0.5 microns), and ultrasonic vibrations may cause it to peel, bubble, or discolor. The same applies to white gold, as most white gold on the market is rhodium-plated. Unless your white gold piece is unplated, it should not be cleaned ultrasonically.
Related Readings: Gold-plated Jewelry Guide, Unplated White Gold Guide
Ultrasonic Cleaning Suitability Chart for Common Gemstones
| Gemstone | Safe for Ultrasonic Cleaning? | Explanation |
|---|---|---|
| Diamond | ✅ Generally safe | Extremely hard (Mohs 10), durable structure. Avoid if fractured or loose in setting. |
| Salt and Pepper Diamond | ❌ Not recommended | Contains many inclusions and fractures—vibration can worsen internal damage. |
| Moissanite | ✅ Safe | Very hard (9.25), no cleavage, excellent structural stability. |
| Ruby / Sapphire | ✅ Usually safe | Hardness 9, strong structure. Avoid if treated with glass-filling. |
| Spinel | ✅ Safe | Durable, hard (8), no cleavage—great for ultrasonic use. |
| Alexandrite | ⚠️ Use caution | Hard (8.5) but valuable and may contain inclusions. Inspect before cleaning. |
| Emerald | ❌ Not recommended | Contains many fractures, often oil-treated—ultrasonic may worsen damage. |
| Tourmaline | ⚠️ Use caution | Fairly hard (7–7.5), but often includes internal cracks or inclusions. |
| Morganite | ⚠️ Use caution | Member of the beryl family—hard but with cleavage and common internal flaws. |
| Aquamarine | ⚠️ Use caution | Also a beryl—watch for cleavage and internal fractures. |
| Topaz | ❌ Not recommended | Perfect cleavage makes it prone to splitting from vibrations. |
| Tanzanite | ❌ Not recommended | Brittle, with prominent cleavage—can crack under ultrasonic vibration. |
| Garnet | ✅ Generally safe | Moderately hard (6.5–7.5), compact structure, no cleavage. |
| Amethyst / Quartz | ⚠️ Use caution | Hardness 7; safe if untreated and crack-free. |
| Zircon (natural) | ❌ Not recommended | Though hard, it’s brittle and often heat-treated—may fracture. |
| Peridot | ⚠️ Use caution | Hardness 6.5–7; may contain inclusions or stress fractures. |
| Lapis Lazuli | ❌ Not recommended | Layered, porous structure—vibration can cause cracking or breakage. |
| Malachite | ❌ Strictly avoid | Very soft (3.5–4), porous—easily damaged. |
| Turquoise | ❌ Not recommended | Porous, often stabilized or dyed—vibration can alter appearance or cause damage. |
| Pearl | ❌ Strictly avoid | Organic, soft, and delicate—vibration can ruin luster or cause cracking. |
| Opal | ❌ Strictly avoid | Porous, hydrated, and fragile—highly sensitive to vibration and heat. |
| Moonstone | ❌ Not recommended | Displays perfect cleavage—can flake or crack easily. |
| Amber | ❌ Strictly avoid | Organic and extremely soft—can melt or shatter. |
| Jade (e.g., Nephrite, Jadeite) | ⚠️ Use caution | Tough but may be porous or treated; avoid ultrasonic if dyed or resin-filled. |
| Moss Agate / Black Agate | ✅ Safe | Quartz family (hardness 7), stable structure. |
| Black Gold Rutilated Quartz | ✅ Safe | A type of quartz with needle-like inclusions—structure is stable. |
| Fluorite | ❌ Not recommended | Soft (Mohs 4), strong cleavage—very prone to damage from vibration. |
Things to Consider Before Ultrasonic Cleaning Your Jewelry
While most metals are generally safe for ultrasonic cleaning, not all gemstones are. Before cleaning, it’s essential to know exactly what kind of gemstone your jewelry contains, as well as its physical characteristics (such as hardness and structure) and whether it has undergone any treatments.
How can you get this information? If your jewelry came with a certification (such as from GIA, IGI, etc.), it will typically indicate the gemstone type and whether any treatments were applied. If you’re unsure, it’s best to contact the brand’s customer service or a trusted jeweler for confirmation.
🔍 Helpful Tip:
If the gemstone has any visible cracks or the setting appears loose—even if the stone is “technically suitable” for ultrasonic cleaning—it’s best to avoid using the ultrasonic cleaner.
Tips for Safely Cleaning Jewelry with an Ultrasonic Cleaner
- Read the user manual carefully: Different ultrasonic cleaners may have different operating instructions and safety precautions.
- Inspect the gemstone and setting: Before cleaning, check for any visible cracks or damage, and make sure the setting is secure.
- Avoid cleaning gemstones of different hardness levels together: They may collide during cleaning and cause scratches or chips.
- Use proper water temperature and cleaning solution: Warm water (ideally ≤35°C/95°F) is recommended. Avoid harsh or corrosive chemical cleaners.
- Control cleaning time and power settings: Use appropriate power levels and avoid extended cleaning times (usually a few minutes is enough). For jewelry with multiple types of gemstones, try to use a low-frequency ultrasonic cleaner to reduce the risk of damage.