If you don’t have any machinery, you can do it by hand this way:
You have to find a piece of opal that is not too large so that it can be handled easily and has a fairly flat or domed surface.
Buy yourself some wet and dry sandpaper from the hardware store. If you need to take a lot of material off to get to the color or to shape it a bit, you will need to get some 220 grit sandpaper. You can attach the sandpaper to a small block of wood by wrapping it around the block and stapling it or nailing it to the back
You can make another block of wood using 320 grit sandpaper, then 600 grit, and finally 1200 grit.
You can then stick some split chrome leather (http://en.wikipedia.org/wiki/Leather) to another block of wood. You might have to ask someone in a shop that repairs leather goods to find out what this is. It’s usually green tough leather, rough on one side.
You have to get some cerium or tin oxide for the final polish. You can get it from a lapidary (stone cutting) supplier, or someone who has to polish scratches out of glass. People who make headstones for graves also use it and maybe people who do terrazzo polishing of tiles.
If you want to get a bit more sophisticated you can buy one of those dremmel machines from the hardware store which gives you a whole bunch of little wheels. In this way you can cut the sandpaper and the leather into little discs, and stick them on to rubberised mini discs that come with the machine. You can use the rubber from old bike or tyre tubes for this.
Get some contact cement from the hardware store for all your sticking needs but if you are using a mini disc, first you cement the rubber on to the disc with contact cement, then stick the sandpaper onto the rubber using disc cement which is like contact cement but remains sticky. Remember to allow the contact cement to dry overnight before putting the sandpaper on or it will be too tacky.
When sticking with contact cement, you put the cement on both sides of whatever you are sticking together and let it dry for about fifteen minutes before pressing the two surfaces together.
You will have to do it this way when you cement the leather on to the rubber. Then you make slurry with water and cerium oxide and put some on the leather. You can also put some on the opal you are polishing.
Just experiment until you get the hang of it. Just make sure all fine scratches are out of the opal before you attempt to polish it with cerium. So this is a method you can use to polish an opal with little or no equipment. Of course, if you want to learn how to do it properly, using opal cutting machinery that you can either make yourself, or purchase, please go to http://opalmine.com/opal-encyclopedia/buyer-and-lapidary-hints-and-tips/ for some advice and a short video. You can also get a cd called ‘Opals for the Ordinary Bloke’ for $35 or free with a parcel of rough opal. This gives you over 30 years of experience in mining, cutting, setting, and marketing opal. If you don’t understand some of the comments made here, just leave a message on the blog at opalmine.