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Frequently Asked Questions
What is a rub?
What cutting machines can I use to cut opal?
How can I start selling opal in my country?
What is opal made of?
Can I use a dremel to polish the opal and carve it?
What is nobby opal?
What is a rub?A rub is an opal piece that has been faced from the rough state on a opal cutting machine to show the approximate color, shape and weight.
What cutting machines can I use to cut opal?What type of opal cutting machines to use.
There are many cutting machines and ways to cut and polish opal. Finding the opal-cutting machine that suites you is the question that most people have on their mind when starting out.
When choosing an opal-cutting machine you have to take into account whether you are going to use diamond grits to cut and polish your opal or sandpaper, pumice powder, and cerium oxide.
If you decide to go all out using diamond grits to cut and polish your opal, you will basically only need three opal cutting machines.
Firstly you will need an opal cutting machine like a pixie or here in Australia we have machine called Gemmasta. These machines are wet machines and will hold all of the diamond wheels you will need to rough shape and polish your opal.
The most commonly used diamond grit wheels in my opinion are as follows
Wheel1: 240 grit hard diamond wheel for roughing out your opal to the approximate size and shape of you want.
Wheel 2: 600 grit hard diamond wheel for the finer shaping on the dop stick to get the shape and dome you want the opal to have.
Wheel 3: A 1000 grit soft nova wheel for smoothening the opal and giving the opal it’s round smoother edges and dome.
Wheel 4: A soft 10,000 or 15,000 grit Nova wheel to give you a final polish,
The thing about diamond wheels is that you will probably have trouble getting a really good polish. They have not perfected the polishing stages yet in diamond.
My advice is to purchase flat lap felt wheel and use cerium oxide with water to brush the cerium oxide using a clean paint brush to apply it onto the felt wheel, that way you will get the best polish possible. (Always re-applying to keep it wet)
The way I cut and polish opal is using hard diamond grits to start with, but then once I have finely cut the opal to the approximate size and shape, I then change to a flat lap 1000 grit wet and dry sand paper with cushioning as backing. (You must wear the sandpaper down with potch to get the right smoothness) This technique is an old fashion way but still I think the best and cheapest way to go.
Always using this part of the process dry. (A dust mask is handy to use)
Once I have sanded the stone I use a felt wheel with pumice powder and water to get the pre-polish, final shaping and adjusting done.
Make sure you wash the opal and your hands really wel so you don’t get impurities in the final polish otherwise you will get scratches in your opal
And then I polish with cerium oxide to finish the opal.
The back of the stone is smoothened out by re-gluing the opal upside down on the dop stick and smoothing the back to as fine a polish as you would like, sometimes giving you a double sided polished opal.
Lastly to become a great opal cutter I think it is important to own a slicer, to slab or split and take excess opal that is not needed away from the nobby.
A slicer also helps when the rough opal piece would be better cut into 2 stones.
Or there is more than one colorbar in the piece.
I hope this has been useful to you.
How can I start selling opal in my country?Starting an opal business is just like starting any other business. It's mostly about people, If people like you and what you stand for, they will buy from you.
You can start selling at local markets and jewellery stores, or once you have trust you can start leaving you opal on consignment with jewlellery stores.
Once you established your market. It's all up from here. What is opal made of?Opal is made of silica spheres that are collected together in conglomerates and fissures in the ground. WHen the rain falls the water carries the silica shperes throught the ground until it fills a cavity in the ground and turns into opal.
When the spheres are stack very neatly (done by mother nature) thus creates color.
When the spheres are large and small and stacked unevenly, you get opal with no color called potch. Can I use a dremel to polish the opal and carve it?Dremels are used mostly for carving opal and taking sand spots out of opal.
They are a very handy tool to have if you are working with opal. What is nobby opal?Nobby opal is a form of opal that comes from Lightning Ridge only. It takes the form of a rounded cavity underground instead of a fault line that seam opal is formed in. This nobby opal has produces some of the best quality black opal in the world.
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