Posted in response to Raw stones from Chari on August 19, 2006 at 18:37:07:

Re: Raw stones Hi Chari Since both rubies and sapphires are varieties of the mineral corundum, which is a VERY hard mineral (9 on the Mohs scale of 1 to 10) they are not easy stones to grind, sand, and polish. Depending on what you have, and what you want done, there are two ways you can go about it - both of which require special equipment. (There are no simple, inexpensive, ways to bring stones of this hardness to a polish. - Some softer stones can be "hand-worked," but not corundum; you'd be "a year and a decade" getting to the polish stage... :~{ ) The first approach would be to cut a small flat in the stone(s) and then lap the flat(s) on a lapidary's wheel set or flat lap, starting with a coarse grit and working down to finer grits until they are ready to be polished on the buffing wheel. Typically the sequence is: 80 grit - 120 - 220 - 600 - 1200 - then polish; or some similar series of increasingly finer grits in that range. The second approach is to tumble them in a rock tumbler. You again start with a coarse grit and run the batch through increasingly finer grit runs until you finally run them with a polishing agent. The tumbler method will polish the entire surface of each stone (or nearly so...) - while the lapping method will only give you a polished "flat" on each stone. The tumbling method is also cheaper - requiring less equipment, just a tumbler. But it will also take MUCH longer: A stone can be lapped to a polish in a day or less; while tumbling them - even in the faster vibrating tumblers (as opposed to the slower rotary tumblers) - will take at least several weeks. (It could be several months if you use a rotary tumbler.) Now that you know that the processes is rather involved and expensive - especially if you don't plan to get into working stone as a long-term hobby - you might want to consider finding a mineral or lapidary club in your area and seeing if one of the gang there would polish the stones for you. Some clubs even have club-owned equipment that members can use - so you could join and do the job yourself there. There is a link to a club list on the Table of Contents page here at Bob's. It is organized alphabetically by state. Perhaps it is worth having a look at that to see if there is a club near you that you could try. Personally - knowing the expense, time, and skill involved - I would not invest in the special equipment needed for a one-shot project. I'd try to find someone who has the equipment and see about getting it done by them. Regards Alan From Alan - August 20, 2006 at 09:01:35 Message: 52815

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