Spinel - Sri Lanka, 7-8 hardnessSpinel - Sri Lanka, 7-8 hardness

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.

3 Minute Read

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 mandarinWhether 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

TinLinde A/Aluminum/Cerium Oxidewater19
Tin50-100k diamondoil or water17
Ceramic50-100k diamondoil13
BATT50-100k diamondoil or water8
BATTLinde A/Cerium Oxideoil or water6
Lucite50-100k diamondoil or water5
DynalapCerium/Aluminum Oxide>water5
Last Lap14-50k diamondoil4
LuciteCerium/Aluminum Oxidesoapy water3
Copper50-100k diamondoil or water3
TinLinde Aoil2
Cast Iron100-200k diamond bortolive oil2
Ultra LapAluminum

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