Caring for Lab Grown Emerald, Ruby and Sapphire
Lab grown ruby and sapphire are corundum, hardness 9, with no cleavage; they tolerate an ultrasonic bath. Lab grown emerald is hardness 7.5–8 but brittle, and ultrasonic vibration can loosen the inclusions and cracks inside the stone. The cleaning rules are not the same.
Three stones, two sets of rules
Coloured stones get lumped together because they sit in the same display case, but their physical properties are not close. Ruby and sapphire are the same mineral — corundum — at hardness 9 on the Mohs scale, with no cleavage planes to split along. Emerald is beryl, at hardness 7.5–8, and it is brittle: it holds internal fractures and inclusions that give it its character and also its weakness.
That single difference decides how you clean each piece. A method that is routine for sapphire can damage an emerald in one session, and not always visibly at the time. The crack may open slowly over months.
Why emerald cannot go in an ultrasonic cleaner
An ultrasonic bath works by creating millions of microscopic bubbles that collapse against the surface, lifting dirt away. On a hard, homogeneous stone this is harmless. On a fractured stone it is a vibration test. The energy travels into the inclusions and along existing fissures, and repeated exposure can widen them or shake a filled cavity loose.
Many emeralds — natural and lab grown alike — are treated to improve clarity, and the filled material does not behave like the surrounding crystal. Ultrasonic energy and heat are exactly what such fills tolerate least. Even where a stone is untreated, the industry advice is the same: no ultrasonic, no steam, no boiling water.
Ruby and sapphire: what is safe
Corundum is robust. Warm water with a drop of mild washing-up liquid and a soft brush is the default, and an ultrasonic bath is acceptable for a clean, untreated lab grown ruby or sapphire in a sound setting. Steam is also generally tolerated. What corundum still does not like is impact — hardness resists scratching, not a knock against a door frame — and it can chip at a thin girdle or a sharp point.
The caveat is the setting, not the stone. An ultrasonic bath will also vibrate the claws. If a claw is already loose, the cleaner finds out before you do. That is why jewellers check the setting before cleaning, not after.
Acids, alkalis and the things in your bathroom
Household chemistry matters more than most people expect. The table below is a rough guide to what sits on a bathroom shelf.
| Product | pH tendency | Effect on coloured stones |
| Mild washing-up liquid | Near neutral | Safe for all three; the standard choice |
| White vinegar, lemon juice | Acidic | Avoid on emerald; fine briefly on corundum, but no benefit |
| Bleach, chlorine | Strongly alkaline | Avoid entirely; attacks metal and can dull stone surfaces |
| Hairspray, perfume, sunscreen | Variable, often solvent-based | Leaves film in the setting; apply before wearing, not after |
| Ammonia-based cleaner | Alkaline | Acceptable for corundum in short dips; never for emerald |
Silver and gold are also affected. Chlorine attacks the alloy in sterling silver and can pit 925 surfaces over time, which is one more reason not to wear fine jewellery in a pool.
Cleaning around the setting
Most of the dirt is not on the stone's table; it is underneath, in the gap between the pavilion and the metal, where soap and skin oils collect. A soft baby toothbrush reaches it. Work gently at the junction rather than scrubbing the stone, and rinse in a bowl of clean warm water rather than under a running tap — a loose stone down a drain is a permanent loss.
For an emerald, use a barely damp brush and blot dry with a lint-free cloth. Do not soak it. Do not leave it in water while you do something else. For a pavé or bezel setting, a cotton bud moistened with clean water lifts film from the crevices without pushing debris further in.
Drying and storage
Dry the piece fully before it goes back in the box; trapped moisture dulls metal and encourages tarnish on sterling silver. Store coloured stones separately, in their own pouch, so a harder stone cannot scratch a softer one — a sapphire will mark an emerald without any effort at all. Keep the box out of direct sun and away from radiators, since repeated heat cycling is unkind to filled stones.
A short routine that works
Wipe the piece with a dry cloth after each wear. Clean properly once a month with mild soap and a soft brush. Have the setting checked once a year, or immediately after any knock. Take the ring off for swimming, gardening, gym work and washing up. Those four habits do more than any specialist product.
What we make
Holycome has run its own factory in Guangxi since 2008, producing in 925 sterling silver, 9K, 14K and 18K gold, and PT950 platinum. Our lab grown emerald, ruby and sapphire sit alongside GRA D colour VVS1 moissanite and IGI-certified lab grown diamonds. Pieces run from $17 to $2,020, median around $98.
If you are unsure which cleaning method suits a particular piece, ask before you try it — we would rather answer a question than replace a stone. Orders over $99 ship free, otherwise $5.99. Returns are accepted within 30 days on unworn pieces in original packaging; custom and engraved work is excluded.