Polishing Kunzite (Spodumene)
With great difficulty sometimes. I have had pieces of Kunzite that cut with no problem and I have cut some Kunzite’s that were nothing but problems. All the rough is different and it is hard to tell how it will cut until you try. Have some aspirin close at hand, you will probably need it.
Step #1 – Go to nearest wall and your bang head against it, repeat as needed during cutting process.
Important: Set the Kunzite down before you bang your head, it is shock sensitive and you may damage it when banging your head.
I would tell most new faceters to move on to something easier. Be aware that the color of Kunzite is UV light sensitive and will fade to clear with exposure. Which makes Kunzite not really worth cutting to me unless you just want a challenge and a sore forehead.
Kunzite is also soft and because of cleavage will generally wear very poorly in jewelry. If you have to set it in jewelry, a pendant or something that is protected is about the only way. Expect to have to replace the stone sooner or later if it is worn much. Kunzite has no real commercial value, except for a few collectors because of the color fading and poor wear. So do not plan on making money cutting it.
If you want a challenge and sore forehead here is how I cut Kunzite. If you have to saw, use a high quality thin blade and a saw with as little vibration as possible. Leave plenty of room from where you saw to where you want to cut the stone out of. Fractures are very common after sawing and it is generally a good idea to wait a day or so before you start cutting to wait for the fractures to appear. Then cut them off with a fine lap.
Kunzite should be cold dopped this is one of the few materials that I recommend it for. It’s a very good idea to have a bottle of the glue solvent handy. So you can unstick yourself from most of the things that you touched while using the glue. In extreme cases, if you glue both of your hands together, it is handy to have a friend close by that will take pity on you and help get you loose. After they get done laughing at you, of course.
You will have to oriented for the best color and cleavage plane(s), the “c” (is best color usually) axis needs to be almost perpendicular to the table, but not quite (like Topaz). This material has perfect cleavage and needs to be worked on a very fine lap, nothing more aggressive than a well worn 600 or finer.
Any shock will cause cleavage separations and problems in general. Be gentle and patient and with a little luck you will finish a stone. Polish with an Ultra lap (Spectra or alumina), tin/lead lap with tin oxide or a wax lap.
As a note of interest I know several Afghanistan gem cutters that work with Kunzite a lot. They tell me that they use a tin lap with 14,000 diamonds for a final polish. Their stones, that I looked at appeared to be polished quite well.