Cutting and Polishing Opal Rough

Cutting and Polishing Opal Rough

Opal Cutting and Polishing Opal Rough is not as Difficult as you Might Think

Opal Cutting and repair Tips – read the book

Opal is one of the easiest stones to cut. The trick is chasing the color to make sure you approach the color from the right direction. Lapidary clubs are a good resource for new opal cutters. Ask experienced members for advice on the basics of cabochon cutting.

Your first task is to search an opal for any hint of color. Then, you use a wet grindstone to grind off the potch until you can see where the color is going. When you’ve exposed enough color, you can choose the top and bottom for your stone based on where you see the best color contrasted against the background color.

Let the stone dry then check for cracks and imperfections. Everyone wants to cut a big stone, but two or three smaller perfect stones are a better choice than one big stone with imperfections. Remember too, if you’re planning to make a jewelry piece, settings come in standard, calibrated sizes.

Unless you’ll be making a completely custom set, you’re better off sticking with a common size. A diamond blade, 10 thousandths thick is a good choice for cutting an opal stone to size.

Many lapidaries will tell you to run the diamond blade slowly with opal. This is a big mistake. Opal is not a hard material like agate, for example. Opal slicing is best done either in water or with water passing over it at the speed achieved from an ordinary 1440 RPM, 1/4 H.P. motor with a 6″ pulley on the motor and a 1 & 1/2 pulley on the shaft.

If you don’t force the stone and you have plenty of water passing over it, you will not cause any damage. In fact, your diamond blades will last longer because they will not buckle as easy. After you’ve cut the stone into the basic shape, use a wet grinder to finish shaping and remove rough edges.

Opal cutting and polishing opal rough – final steps before polishing

Cutting and Polishing Opal Rough
opal sanding wheel
Cutting and Polishing Opal Rough
peter at the opal grinder

What to do if your opal cutting and polishing opal rough has been completed and there is a scratch. Repairing or mending scratches in finished and or mounted opals.

If you have a piece that has become scratched or dull, just use the finer papers (700 or 800 grit) you can try to work the above process by hand by cutting small strips of the sandpaper and just rubbing them back and forth across the stone until the scratches are taken out.

If the paper is too harsh, just tone it down by rubbing it on a piece of glass. Next step is to get a piece of old sheet or pillow slip (cloth) and vigorously polish with tin oxide or cerium oxide.

If you want to polish the gold or silver at the same time, use some metal polishing pastes. Most of these items can be purchased from the hardware store, with the exception of the oxides which may only be available at Lapidary supply stores or at workshops that polish gravestones. (Stonemasons) (Check in your yellow or pink pages on the telephone directory for locations.)

*potch is unformed opal

Go to watch a video on how a professional does it, using the correct machinery. So as you can see by these few simple comments, the opal cutting and polishing of opal rough is not so difficult. Of course like all skills, it takes time to learn, and we can help you along the way. just leave a message on this blog page if you need some more directions.

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2 thoughts on “Cutting and Polishing Opal Rough

  1. desde Honduras interesado en iniciarme en el arte de cortar y pulir opalo, herramientas y materiales.

    1. sorry but my instructions are only in english: lo siento, pero mis instrucciones son sólo en Inglés: and

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