This is a new video to replace a really old one on opal cutting using diamond Nova wheels. Many people ask about the difference between cutting opal with sand paper and using diamond impregnated soft wheels.
So why use diamond Nova wheels? In the old days we used pumice on felt but it was messy and cumbersome. The Nova process is a wet process which, because the wheel is soft, is designed specifically for making cabochons.
Dopping your rub
That sounds a bit rude doesn’t it?! You know the basic drill. We attach the opal to the dop stick using wax. See this video for more on this subject.
TIP: Make sure the opal sits level on the wax and perpendicular to the dop stick as this will assist you in getting the perfect shape and dome when polishing.
320 Grit Hard Diamond Wheel
This wheel is used to shape your stone and to remove the initial cutting facets that probably occurred on the previous wheel. Keep turning the opal around shape it from the side all the way up to the top of the face.
TIP: Make sure you look over the top of the opal to ensure you are getting a pleasing shape. Another way to check under the lights is to make a rough open fist around the stone giving you a dark backdrop to again check the shape.
So how do you remove those facets? The secret is SPEED! Moving fast across the surface whilst you polish will even everything out. Remember the more you do in this stage will set you up nicely for less to do in the next stage and with a great final result.
600 Grit Nova Wheel
Nova wheels are cushioned and meant to give a little making them perfect for shaping cabochons.
Ensure as you are polishing that you try and maintain a nice setting edge for the jeweler by rolling the sides inward so they have something for the claws to grab on to and the stone can be set securely.
Again in this stage you will use speed as you roll the stone from top to bottom. By spinning the opal fast you ensure a smooth surface.
1200 Grit Nova Wheel
This is the final pre-polish on a Nova wheel. Now on this wheel you would expect that your shaping has been done and we are working only to get the scratches out. The area that gets most neglected at this stage is the edge of the face as it has the least amount of surface area touching the wheel. Make sure you concentrate on this and a final fast polish is completed.
Final polish with a felt wheel and cerium oxide
Not to go against my earlier dismissing of using felt and pumice, I do think that the cerium oxide and felt wheel gives a much superior polish to anything else out there. We add the cerium oxide to water and paint it on the wheel until is it waterlogged.
TIP: Paint on the cerium and water mix until it starts splattering you. Keep up this level of saturation for the duration of the polish so that you don’t burn or crack your stone with the heat created by friction.
You don’t need to apply that much pressure whilst polishing and the process should be fairly quick if you have put the work in on the earlier wheels.
Once you are completely happy wit the polish, remove the opal from the dopstick and repeat on the back of the stone.
FINAL TIP: If you have residual wax on the opal, use your methylated spirits (metho to Aussies, denatured alcohol or spirits to the rest of the world!) to melt the wax without harming the opal.
And there you have it – how opal cutting using diamond Nova wheels is the most successful way (in my humble opinion)!