How to Polish Gems of 7-8 Hardness: Survey Results
Some very popular jewelry stones, such as beryl, quartz, and topaz, fall in the 7-8 hardness range. You can find polishing recommendations for these stones in our IGS member survey results.
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Editor’s Note: Some years ago, the International Gem Society (IGS) conducted a survey of members’ gemstone polishing techniques. In this article, you’ll find the results for polishing gems in the 7-8 hardness range. This range includes very popular jewelry stones, like emerald, quartz, spinel, topaz, and some garnets like malaia and mandarin. Whether you’re just starting to learn the art of gem cutting or just looking for a new way to tackle a problematic gem material, we hope these results provide some useful suggestions.
For more information about the survey or to find results for more gemstones, click here.
Polishing Techniques for Gems of 7-8 Hardness
| Laptype | Polish | Lubricant | Votes |
| Tin | Linde A/Aluminum/Cerium Oxide | water | 19 |
| Tin | 50-100k diamond | oil or water | 17 |
| Ceramic | 50-100k diamond | oil | 13 |
| BATT | 50-100k diamond | oil or water | 8 |
| BATT | Linde A/Cerium Oxide | oil or water | 6 |
| Lucite | 50-100k diamond | oil or water | 5 |
| Dynalap | Cerium/Aluminum Oxide> | water | 5 |
| Last Lap | 14-50k diamond | oil | 4 |
| Lucite | Cerium/Aluminum Oxide | soapy water | 3 |
| Turbofan | water | 3 | |
| Copper | 50-100k diamond | oil or water | 3 |
| Tin | Linde A | oil | 2 |
| Cast Iron | 100-200k diamond bort | olive oil | 2 |
| Ultra Lap | Aluminum |
…
International Gem Society
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