Saving Precious Stones from the Plumber’s Wrench

A recent question from an amateur jeweller is the inspiration behind this post.

The questions are

‘How to stop precious gems and small jewellery going down the sink?’


‘How to find diamonds at the bottom of a dirty ultrasonic cleaning tank?’

As a diamond setter, each and every time we set a stone the final test is to run it through the ultrasonic cleaner.  Naturally, this cleans the setting nicely before presenting it to the customer, but since it also  gives the setting a serious workout, for us it also serves as a practical test of how securely the stone has been set.  We often clean settings in the ultrasonic cleaner before working on a new job, so we can have a real good look at the piece before we start.

Every now and then the ultrasonic cleaner will loosen dirt which turns out to be the only thing that was holding a stone in place in its old setting – and the setting and stone will part company.  If that happens at the start of the day, when the cleaner’s tank is still pretty clean, it’s a very simple task to find the stray stone.  But after a big day, with lots of gunk floating about in the tank, it can be a major search and rescue operation.  What’s more, fishing inside a really dirty tank is not our idea of fun.

It’s worse, of course, to empty the tank, only to discover, too late, that the stone has gone down the drain.  The embarrassment of calling in the plumber will only be slightly less than telling the customer you’ve lost their diamond.  Clearly, these are situations we would all prefer to do without.

Avoiding the Loose Stone Scenario

Here’s how to avoid the problem in the first place:

  1. Place suspect pieces inside a small vegetable sieve.  Most kitchens have such items in a bottom drawer – the cheap plastic style with nylon weave is perfect.  HINT. If you don’t have a sieve an old lady’s stocking will do fine – just tie a knot in one end to hold the piece secure.
  2. Put the sieve, with setting/stone, inside the basket and run through cleaning cycle as required.  At the end of cleaning cycle remove the sieve and make sure the setting and stone are intact.  If the stone has come loose then at least it has been contained in the sieve and you can have it reset.  NB Do not heat the tank  – if you notice the sieve getting floppy, remove it promptly.
  3. If you forget to use a sieve, just make sure you do not dump the tank water without checking you have the stones first.  If you do lose a stone in the cruddy tank water, do not despair – read the hint below.

Finding and Retrieving Lost Treasure

OK.  You now have a clean setting, but it’s missing an expensive stone which you need to find before the owner comes to collect it.  Here’s the procedure:

  1. Do not dump the tank water.
  2. Apparatus: You will need to acquire two items:
    1. a large glass (see through) jar or bottle
    2. a big blob of bluetack
  3. Switch off power to the ultrasonic cleaner at the unit and at the powerpoint.  Detach lead from machine.  NB If water level is high you may have to remove some from the top – you will be inserting the jar or bottle, which will displace some water.  You don’t want spills from water going over the side of the tank.  HINT.  If you do need to remove water, drain from the top of the tank to minimise risk of scooping up the stone you are searching for.  Before dumping this water we would recommend pouring it through a fine weave sieve as well.  Check that the stone is not in the sieve before going any further.
  4. Firmly attach the blob of bluetack to the bottom of the jar or bottle.  Remove the basket from the unit.
  5. Carefully push the jar or bottle towards the bottom of the tank.  As the object goes deeper into the water, most of the crud will simply move away.  Through the glass bottom you will be able to examine the bottom of the tank for any objects that have fallen.
  6. Once the stone is found, steadily press the bluetack blob into the stone until it is firmly held against the glass base.  Then carefully remove the stone from the water.  Your salvage operation is now complete.
Liquid Glass Oz designs quality ultrasonic cleaners for commercial operations in Australia and New Zealand (N18973)

Setting Up Your Ultrasonic Cleaner

OK.  You’ve bought your new ultrasonic cleaner and you want to know how to set it up.  There’s a trick to doing most things – and this is no exception.  A little time spent following a procedure could save you a lot of money!

Protecting Your Investment

Inspect the box for damage before opening it.  If outside shows any sign of rough treatment during transport, take photos – they might be needed to show the supplier or freight company for a claim.

  1. Take more photos of the unit and anything inside the box if they have been damaged in transit.  Take a clear image of the unit’s serial number.
  2. Inspect contents. Take particular note of the tax invoice and the unit’s user manual/operations guide.  Often the items supplied will be specified in the user manual.  Check you have them all.  If not, contact the supplier ASAP and ask for anything that seems to be missing.
  3. Tax Invoice  A valid tax invoice will show GST included in the sale, the supplier’s Australian Business Number (ABN) and address in Australia.  The tax invoice is a valuable document which should be kept safe and produced (or copied) if you ever have any warranty issues.   Some sellers on Ebay will provide a tax invoice which is generated through their system.  As long as the document meets the requirements set out in the New Tax System (GST legislation) it doesn’t matter what it looks like.  This contrasts with invoices/shipping documents that make no mention of the words tax invoice, GST included in the purchase and the supplier’s ABN.  We recommend caution if dealing with a supplier who ships cleaners without a valid tax invoice, because it is extremely unlikely that you are dealing with a registered Australian business who can be forced to adhere to Australian consumer protection laws.

Product Safety and Compliance

Once you know you have everything that’s supposed to be included, you can move on further.  The next step is about checking your unit is safe for you and your staff.

  1. Check the power lead provided with the unit has an approved Australian/New Zealand style plug – sometimes suppliers will provide one that fits in the socket, but it does not have the insulation on the top pins (normally black).  Plugs without visible insulation on the top two pins are the ‘old style’ which ceased being approved for sale in the late 1990s.
  2. Check for C Tick label.  Electrical equipment needs a C Tick label to identify the authorised supplier and to show that the supplier can prove the device meets Australian/NZ EMC requirements.  By law ALL ultrasonic cleaners sold in Australia and New Zealand must have this label, whether imported or manufactured locally.  They also require the supplier’s electrical code (usually a number starting with letter N or V, representing the state the company is registered in).   NB If the unit does not have a C Tick and the supplier’s electrical code, then it is illegal for sale in Australia and New Zealand and it may also be unsafe.  Contact your local Department of Fair Trading and request a refund from the supplier.
  3. Check power supply.  Most quality units will be manufactured for 240Volt mains supply.   Many units will state 220 or 230 Volts, or some range between these.  The closer to 240 Volts the better.   If the unit is labelled less than 220 Volts its working life can be much less than one made for 240.  NB Do NOT attempt to use a device made for US power supply (110 Volts).  Return it f or replacement or refund.
  4. Use a surge protector. Even robust commercial ultrasonic cleaners can fail due to power surges.  Like computers, these days, ultrasonic cleaners all have electronic components which can easily burn out when power spikes occur.  We recommend taking sensible precautions, like using a quality surge protector at all times and to remove the device from the power outlet during electrical storms,  or when you are absent from the workplace..

User/Operating Manual

Most suppliers will provide a user or operating manual.  Manuals from quality suppliers units will be in plain English that the average person can understand.  Often the manual will also specify the unit’s warranty and support arrangements.   We recommend against items that must be sent overseas for warranty service.  The following points are obvious, but we’ve all seen the line – if all else fails read the manual.

  1. BEFORE you connect the unit to the power supply, or attempting to use it ensure that you read the manual and understand it.
  2. Follow the instructions in the manual.  If you don’t, often the manufacturer’s warranty will not apply.  It could be an expensive mistake.

Next Step

After you have set up your machine as per supplier’s user manual, you should immediately test its function.   Run a simple foil test to satisfy yourself you have a true ultrasonic cleaner, not a dud.  If the machine fails the test contact the supplier and have it replaced/get a credit.


  1. EMC is Electro Magnetic Compatibility. When a product shows the C Tick symbol it tells the consumer that the supplier has proven that the device meets the Australian/New Zealand regulations for EMC.  A product that does not meet EMC rules may interfere with radio and other communications, including devices such as pace makers and other sensitive life saving equipment.
  2. The supplier’s code (usually a number starting with letter N or V) on an electrical product tells the consumer that the supplier has tested the device for compliance with the Australian/New Zealand regulations for electrical safety.  The CE label often seen on electrical products has not value in Australian/NZ.  It is easily confused with an almost identical CE label which represents Chinese Export.
Liquid Glass Oz designs quality ultrasonic cleaners for commercial operations in Australia and New Zealand (N18973)

Cleaning Tarnished Jewellery

A customer asked how to clean her sterling silver jewellery in an ultrasonic cleaner

Even quality sterling silver, no matter where it was bought, can get those ugly black marks that spoil the appeal of expensive jewellery.  After working in the jewellery trade for more than 2 decades we can say that this is a very common occurrence.   The ultrasonic cleaner will clean contaminants very well, but it will not remove tarnish on its own.
Here’s a hint for handling tarnish and this is the way we handle it ourselves when we have a piece so affected
  1. Teaspoon of ammonia in the tank with the water.
  2. Run jewellery through a single cycle.  Do not throw out tank solution yet.
  3. Inspect jewellery.  If still not properly treated leave the item to soak in the solution – just as it is for say up to 30 mins.  Do not throw out tank solution yet.
  4. Inspect again.  If still not to your satisfaction next step is to grab an old furry toothbrush.  Wrap a soft cloth around the bristles.  Dip brush in the tank (still with the ammonia solution).  Gently rub the section that is tarnished.  In our experience this will get rid of the tarnish 99% of the time.  For the other 1% – try upping the concentration of ammonia and repeating the procedure from 3 above.

For best results rinse item using distilled or filtered water.  Domestic tap water can contain lime and scale which dries to form a messy film.  Not a good look on your jewellery.

Liquid Glass Oz designs quality ultrasonic cleaners for commercial operations in Australia and New Zealand (N18973)