A cluster of seven gem-quality topaz crystals attached to their feldspar matrix. You could facet these topaz gemstones. But would you? “Topaz” © Rob Lavinsky, www.iRocks.com. Used with permission.
Question
I know the distinction between gems and minerals has a lot to do with human judgment. Gems are typically minerals that we value as beautiful. But what’s the difference between “gemstone rough” and “mineral samples?” I’ve seen many mineral samples for sale that I thought would make beautiful cut gems, but they are worth more as mineral samples. When I’m rock hounding, how can I tell if the crystals I find are facet rough?
Thanks,
Mel
Answer
As far as faceting goes, the most important distinction between gems and minerals is clarity. Most crystals aren’t clean. That immediately reduces their value as facet rough.
If you find a crystal with a large clean area, then you get into aesthetics. Whole crystals are much rarer than broken pieces. If the crystal (or crystals in a cluster) are in good condition, and especially if it has some of the original matrix attached, then you’ve found a rare prize. It would be a shame (maybe even immoral) to cut specimens of this quality, as there are so few. Great finds like these are worth more whole.
You’ll rarely encounter this situation. Few mineral specimens actually have the clarity needed for faceting. However, gems and minerals don’t have to be cut to be appreciated for their beauty.
Donald Clark, CSM IMG
Covellite is a very attractive crystal, but it’s too soft to facet. “Covellite (latest Cretaceous to earliest Tertiary, 62-66 Ma; Leonard Mine, Butte, Montana, USA) 5” by James St. John is licensed under CC By 2.0
 | Topaz Value, Price, and Jewelry Information |
 | Feldspar Value, Price, and Jewelry Information |
 | Covellite Value, Price, and Jewelry Information |
