Classifier Mesh Sizes

Posted November 16, 2014 By Admin

Classifiers are used to size material accurately for classification – often used by gold prospectors who need to size concentrate for use in spiral wheels or the like.

  • 1/2 inch (the largest screen) is about 4 holes per square inch (use to remove worthless larger rocks)
  • 1/4 inch is about 16 holes per square inch (use to reduce size of gravel material for easier sluicing or panning)
  •  1/8 inch is about 64 holes per square inch (use for final clean up of gold concentrates from black sand or for recovery of small gem stones)
  •  1/12 inch mesh – good all around size.
  •  1/20 inch – FINE MESH is about equal to window screen (use for final clean up of FINER gold from your black sand or for recovery of very small garnets and gemstones, etc…)
  •  1/30 inch  – SUPER FINE MESH – a very tight weave
  •  1/50 inch – VERY FINE MESH – 2500 holes per square inch- OFTEN USED WITH #30 and #70 screen for BLUE BOWL CLEANUP
  •  1/70 inch – VERY FINE MESH – 4900 holes per square inch – use with the #6 (1/30″) and #7 (1/50″) screens for best blue bowl recovery.
  •  1/100 inch – the smallest screen – use for microscopic gold recovery and ultra fine gold dust and flakes.

Note that the standard pair of gemstone sieves will almost always be 1/4″ and 1/8″ – you can quickly go through the larger material on the top sieve and then anything that goes through the bottom sieve will usually be too small to worry about.

See the photo gallery below to get a feel for what these mesh sizes look like in reference to a metric/inch ruler.



Lapidary – where to start?

Posted October 16, 2014 By Admin

We often get calls from people who are interested in rocks and gems, would like to get started in the lapidary hobby but dont know where to start. It is a good question but a very BIG one that will need some research first.

First question is why type of work are you interested in?  Tumbling, Carving, Cabbing or Faceting?  Do you need a diamond saw to trim or slab your rock?  Depending on your interest and available budget, you will need to pick from one or more of these main categories to set up your lapidary workshop.

Selection of tumbled rocks ready for craft or jewellery making (photo from Aussie Sapphire)


  • TUMBLING – low entry cost and easy to learn.  Use your tumbler to turn rough rock into free form polished gemstones that can be used in various craft projects or drilled/strung or wire wrapped to make jewellery.

Tumblers are available in a range of sizes. You will need a starter kit of grit and polish plus time – it usually takes around 4 to 6 weeks to complete a batch of rock in a rotary tumbler.

More information:


Please read the FAQ ARTICLE HERE to learn more about the process or BROWSE OUR RANGE HERE.




Example of carving from

CARVING – low to medium entry cost although a little trickier to learn.  Carving is usually done using some type of rotary tool (dremel, micromotor, flex shaft or similar) fitted with appropriate carving burs and polishing bobs.

Create free form or carved shapes from rough stone – anything is possible here with the only limit being your imagination. Carve abstract or realistic shapes (animals, plants, religious motifs, etc). Pieces can be for display or drilled/set for jewellery.

Dremel kits can be purchased very cheaply at large hardware stores – all you will need to add are some diamond tools and polishing bobs/polish.  SOME SUITABLE ACCESSORIES ARE LISTED HERE.





A selection of cabochon gemstones from article.

CABBING – medium to high entry cost. Use a flat lap or cabbing arbor to create cabochon gems (usually flat bottom and domed top) – opals are the most well known cabochon gemstone but just about anything can be cabbed including gems that are more typically faceted. Can be regular shaped or free form – if you cut in a regular calibrated size, then your cabs can be set in a blank jewellery setting at very reasonable cost.

At the budget end of the range, we offer flat laps for cabbing – the machine will drive one horizontally mounted disc (6″ or 8″) and you will go through a series of steps to grind, sand and polish your cabs. A bit cheaper and more compact but not quite as convenient.  If you have a bit more money to spend, you may prefer a cabbing arbor which has a series of vertically mounted wheels in 6″ or 8″ diameter so you can move through the steps on the one machine. A 6 wheel arbor is most popular but if your budget is more limited, you may choose or 2 or 4 wheel arbor.

BROWSE SOME OF THE OPTIONS HERE – machines can be set up to suit your needs so contact if you have any queries.


Selection of faceted Blue Sapphire from Reddestone Creek mine (photo from Aussie Sapphire)

FACETING – high entry cost and more difficult to learn.

This is the top level of the lapidary hobby – faceting machines are a big investment but is the only way of creating a traditionally faceted gems that you would normally see in a piece of jewellery.  There are a number of different machines around so do your research thoroughly and choose carefully. We highly recommend doing a faceting course or having access to help at your gem club so that you have the help you need as you learn to use your machine. The basics of faceting is not difficult to learn – the process of becoming a master faceter able to create beautiful gems takes longer but is incredibly satisfying.

BROWSE OUR FACETING OPTIONS HERE – note that faceting machines are sold without laps so you will need to factor in the extra cost of the accessories – there are lots of options when choosing a lap kit.



Diamond saws to cut rock from 4″ trim saws up to 36″ slab saws.

CUTTING – most people will need some kind of diamond saw to cut their stone to size. Diamond saws are optional but very useful.

Generally you only need a trim saw around the 6″ to 8″ size but we have slab saws that can handle very large stone. The key thing to consider here is cutting depth – decide how large a stone you need to cut and choose the saw accordingly.

A more detailed discussion on saws is beyond the scope of this article but we suggest you REVIEW OUR COMPARISON VIDEOS ON YOUTUBE HERE to help you select the best option for you.




Once you have narrowed down which area of the hobby you want to focus on, then you can decide which package suits you best.  Buying second hand can help to cut down the cost of equipment – unfortunately, good quality used machinery can be difficult to find as it often changes hands privately within clubs. If you are keen on buying second hand, keep a close watch on Ebay, Gumtree and the classifieds  – good idea also to spread the word that you are looking so others can keep an eye out for you. Keep in mind that there will be no warranty support and sometimes spare parts are unavailable for older machines that are no longer in production.

There is a wealth of advice out there on the internet to help you get started in the lapidary hobby – we also suggest checking out the AUSSIE LAPIDARY FORUM and we are always available to answer any queries you might have.




Cleaning bolts in a tumbler – PART 2

Posted April 2, 2014 By Admin

Part 2 of this article covers use of a rotary tumbler for this job.
Barrel_1Barrel_A_Before2In this test, we have used both #80 and #46 silicon carbide grit as well as medium cut ceramic media (triangle shape) – a bit water is added for the rotary type tumblers – aim to fill the barrel up to about 2/3 full.

This photo shows the batch before it was tumbled – note some of the pieces were extremely rusty and others just greasy and dirty. Again, we would expect better results if parts were degreased before tumbling.

The 12 pound barrel can fit larger pieces in compared to the Gyroc tumbler (note the large cog which was too large for the Gyroc A) has cleaned up well in the larger 12 pound barrel.  As a size reference, the base of the purple sieve is about 10″ (250mm).

Compared to the Vibratory tumbler, the bolt threads did not clean up quite as well and it took a little longer to get this finish (about 2.5 hours). The Lortone tumbler runs quieter. We used the QT12 for this test but you can get a triple barrel tumbler (same 12 pound rubber barrels) for larger scale tumbling. 



Cleaning bolts in a tumbler – PART 1

Posted April 2, 2014 By Admin

Every now and then we get asked about cleaning bolts in a tumbler so we thought it was time to post a few pictures with extra information.  Tumblers are great for cleaning up all sorts of metal objects as it takes a lot of the tedious hand-work out of the job. There are a few different ways to do it – Part 1 of this article deals with tumbling in a Vibratory tumbler:


This test batch included a selection of old bolts and other items – some extremely rusty, others just very greasy and dirty.

The test machine is a Gyroc A tumbler (the medium size).  In this test, the tumbler was loaded with about 4kg of medium cut ceramic media (medium abrasiveness, triangle shape) – about 4 heaped tablespoons of #80 grit silicon carbide and a small amount of water was added along with the test parts.

The parts were tumbled for about 1.5 hours – just before removing and rinsing, additional water was added for about 10 minutes to make the clean-up easier.  Note that normally we would recommend degreasing parts before tumbling for better results – we did not bother with this small test batch.




After almost 2 hours of tumbling, the parts came out very clean (even better if degreased before tumbling).  However, there are a few things to consider with the Vibe Tumbling Method:

1) Using coarse abrasive grit in a vibratory tumbler will wear the barrel faster than in normal usage.  The tumbling is faster and more effective but you need to factor in more frequent replacements of bowls.

2) The donut shape of the tumbler bowl does restrict the size of piece that can be tumbled – they need to be small enough to move freely around the bowl.

3) Vibratory tumblers are more noisy than the rotary tumblers.


Vibe_B_AfterThese photos show a before and after shot of the pieces (note the large cog was too large to fit and was subsequently tumbled in the rotary batch instead).

There is a little rust remaining on the thread of the largest bolt – this would have been improved by degreasing prior to tumbling.


Rock Tumbling FAQ

Posted November 4, 2013 By Admin

Rock Tumblers are one of our biggest sellers but you may have questions – see the FAQ below and it is very likely you will find an answer.


Time varies but when using a standard rotary (barrel) tumbler, it can take around 4 to 5 weeks of continuous operation. It is usually a 4-step process:- coarse grind, medium sand, fine sand and polish and it often takes around a week per step.


Tumblers are a great way to get started in the lapidary hobby – the process is quite simple and although it takes some time, kids love the end product. An excellent way to learn more about our natural environment.  See this blog article for more info on starter kits.


Apart from a tumbler, you will need silicon carbide grit, some suitable rock polish and a supply of rocks. The silicon carbide comes in a range of grits from coarse to fine. We sell starter kits of grit/polish – Kits A or B are good for about 3 or 4 batches in a 3 pound tumbler.  All components in the kit are available separately so you can restock as needed.  Rocks are readily sourced from the beach, creeks/rivers or keep an eye out for suitable tumbling rock at your local gem show.  Tumblers are listed with optional starter kits or as a complete package deal – just browse here for rotary tumblers of various size.


Some people use coarse river sand instead of silicon carbide grit to grind their rocks. This method can work after a fashion but it takes a lot longer (ie. more electricity) and you have much less control over the process. We do not recommend this method.  Silicon carbide grit is relatively cheap and works much better.


The smaller Lortone tumblers only have a very small motor – they do need to run continuously but they use very little power. The 3A and 33B tumblers have a 0.33 Amp motor – based on 230V power supply and cost of electricity of $0.315 per kW hour, running 24 hours a day will cost around $4 per week.  This is slightly less than leaving an 80 Watt incandescent light bulb on 24 hours a day.  Cost of consumables run at around $2 to $2.50 per week or less if you buy in bulk. If you collect your own rocks, this is a very cheap hobby.


While vibratory tumblers can be quite noisy, the Lortone rotary tumblers use a solid rubber barrel which is extremely quiet. The 3A  has been measured at around 55 decibels which is at the lower end of normal conversation. If you put your tumbler in the garage, you probably wont hear it running at all.


Aussie Sapphire provides full warranty support – the warranty period on tumblers is 12 months and is handled at our NSW office/workshop. In many cases, we can remotely diagnose and provide parts – sometimes it is required to send the machine back for assessment. Warranty issues are rarely experienced – these machines are robust and reliable.  We keep a full range of spares and accessories in stock.


Rotary machines are quite simple and there is not much to go wrong. We recommend oiling the shaft bearings with a light machine oil (Singer Sewing Machine Oil or similar) – just a drop or two every 30 days of operation. At some point you will have to replace a drive belt – these only cost a few dollars and should last up to a year or more depending on usage.


This depends on what size tumbler you buy. A 3 pound tumbler has a barrel of about 10cm diameter and 10cm depth – you fill the barrel up to 3/4 full of rocks so your rocks need to be small enough to move freely within that barrel size. It is a good idea to have a mix of sizes to optimise the tumbling action. If your rocks are larger, then you need to move up to a larger size barrel. Dimensions of the various barrel sizes are provided in the listings. A good rule of thumb is to tumble rocks that are no larger than half the diameter of the barrel along with a generous mix of smaller rocks – probably only one or two of these larger rocks – remember you need sufficient room for the rocks to tumble and grind.


These are very different – if you are just starting out in rock tumbling, we generally recommend a rotary tumbler as these are easier to use for beginners and do not require as much monitoring during use. Vibratory tumblers work faster, use less consumables (grit/polish) but require checking twice daily to monitor correct slurry consistency. Rotary tumblers are slower but can be left to work without fuss between stages and are generally much quieter during operation.


For rotary tumblers, we recommend two starter kits – A or B. Both kits contain the same 3 grades of silicon carbide grit (500 grams each of #80, #220 and #600) – you normally use about 3 to 5 tablespoons of grit per kilogram of rock. You do need to throw out the silicon carbide slurry after about a week of grinding – it is not toxic so you can dry it and throw out in the garbage.

Kit A has 250 grams of Cerium Oxide polish – this one is good for rocks around hardness 6 to 7 which includes the quartz group (petrified wood, jasper, agate, amethyst, etc) or glass (natural or man-made). Kit B has 250 grams of Tin Oxide which is more general purpose and works well on harder rocks such as garnet or topaz as well as the softer rocks – it also contains an additional pre-polish step (500 grams #1500 Alumina) which can help if you are having trouble getting a good polish.  Note that you can recycle polish slurry a few times before discarding.

Both Kit A or B should do around 3 or 4 batches in a 3 pound tumbler. They also contain a small packet of plastic pellets which are used as filler in later stages.


Tumblers are great for metal polishing – we sell many tumblers (both rotary and vibratory) for this job. The most popular tumblers for polishing silver jewellery is the Lortone 3A or the Gyroc Model B. Larger tumblers are generally preferred for polishing brass for reloading. You need different media for working with metal – for polishing only, we recommend stainless steel shot and burnishing compound.  This blog article has more information on using the 3A for polishing jewellery.


We post every day. Note that due to the heavy weight of these items, courier delivery is via Star Track Express – this is a road service and is NOT necessarily faster to some locations. If you need your tumbler in a hurry, please check with us first but it is better to plan your purchase allowing for postage time. You can check postage cost by adding item(s) to the shopping cart and using the shipping estimator on that page – you can do this any time.   We have a range of payment options to suit you – select at the checkout from Visa/Mastercard, PayPal, Bank Deposit or Cheque/Money Order.

Do you have even more questions?  You are bound to find the answer in one of the following websites: