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0 In Gems & Jewelry/ Liz's Life

Memory Stones

If you’re like me, you’re genetically pre-disposed to pick up rocks wherever you go.

I tend to come home from a simple trip to the beach with pockets dragging. I’ve picked up stones in Japan, Greece, Turkey, England, Michigan, Brazil, and on the top of Mt. Vesuvius. They fill bowls and line window sills.

However, you may have the desire to make something of your finds: drill them, tumble them, have them cut into a cab or carving, and set them. But how do you know what might make a good jewelry stone?

First, the stone should be hard.

Well, yes, all stones are hard, relatively speaking. But if you want to cut or tumble it, this means your stone should be higher than a 5 on the Mohs Hardness Scale. The Mohs Scale is a comparative scale of mineral hardness with talc, as in talcum powder, being 1 and diamond being 10.

How do you know if a stone is “hard enough”?

If your stone scratches a knife blade (5.5), it is hard enough to cut and take a good polish. Scratch your stone across the blade. Wipe away the powder to be sure you’ve scratched the blade not just powdered the stone. If the stone scratches the blade easily, its hardness is much higher. If it scratches only with effort, it is about the same hardness as the blade.

Turquoise and obsidian (volcanic glass, apache tears) are on the low end at about 5 to 6. Feldspars (sunstone, moonstone) are 6 to 6.5 Quartz (smoky, amethyst, and citrine) is 7. Garnets and tourmalines are 7 to 7.5. Topaz is 8. Corundums (sapphires and rubies) are 9. Only if you’re rockhounding in the Arkansas’ Crater of Diamonds State Park and find a greasy/shiny stone will you have to worry about stones of 10 in hardness.

Second, look for something without fractures, if possible.

Fractured stones will break during tumbling or cutting. Stones with holes or pits in them will capture grits during the tumbling process. The trapped, coarser grits will continue to scratch the stones as you tumble with finer grits. You won’t get a good polish.

If it has too many fractures, but you love it anyway, admire it on the windowsill. I tumbled an agate I found in the Namib Desert, to my regret. It lost all the interesting wind-sanded skin it had.

Third, look for dense, finely grained stones.

These are your best bet for tumbling, cutting or carving. Stones with large grains—many types of granite, for example — may crumble during cutting or tumbling. They may polish unevenly. If you can easily see the grains, the stone might not be a good candidate for cutting. Rub a couple stones together. If they don’t create a pile of debris, you may have a stone dense enough to work with. If the stone is already shiny—especially if it’s been tumbling in a lake, river, or ocean—you’ve got a winner. Sandstone or rocks containing mica will just make dust.

Lastly, consider size.

Depending on whether you tumble it or have your stone cut, you’ll lose between 30 and 50 percent of what you pick up. Believe me, when traveling, rock size is definitely a consideration. 

Here are some winners.

The best stones for tumbling, cutting, or collecting are agates (including thunder eggs), jaspers, petrified wood, quartz of any kind, obsidian, moonstones, sunstones. Garnets and tourmalines are a price, if you can find them. If you get to Arkansas, I wish you good luck.

One last hint.

Carry a permanent marker. Whatever stone you find, write on it where it was found. They’ll all look alike when you get home.

Have fun.

0 In Gems & Jewelry/ Liz Writes

The Enduring Allure of Gemstone Crystals

This 18k yellow and white gold pendant is set with an amethyst of extraordinary color. Design by Deborah Spencer, Trios Studio, Lake Oswego, Oregon.

As I work on the revision of The Listening Heart—thank you Beta readers for such excellent feedback—I was tickled to find an article in the March/April 2019 edition of Lapidary Journal Jewelry Artist magazine entitled “Crystal Hues Persuasion” by Deborah Yonick. Continue Reading →

0 In Gems & Jewelry

Amethysts and Crystal Power

John Dyer is one of several gemstones artists who have taken cutting to another level. This 68.49 carat amethyst is one of his Dreamscape™ series. Photo courtesy John Dyer & Co.

Perfect gemstone crystals, such a the breathtaking amethyst below, are the jewels of the mineral world. Because of the metaphysical powers attributed to crystals, as well as the real power of quartz crystals, I thought we’d look at that juxtaposition today. Continue Reading →

0 In Gems & Jewelry

Birthstone Friday: Lab-Grown Emeralds

14k yellow gold pendant, set with pear-shaped Chatham-created emerald and small diamond. Courtesy VerbenaPlaceJewelry.com.

Emeralds are some of the most beloved gemstones in the world—especially by those whose birthdays are in May. However, richly colored, unflawed or lightly flawed emeralds are difficult to find and very expensive when they are found. So it was only natural that someone would try to do better than Mother Nature. In the 1930s, Carroll Chatham succeeded. Other growers soon followed.

As they grow in the earth, emeralds are subject to temperature changes, intense pressures, and impinging hot liquids that can burn, melt, crush, or corrode the stones. Violent mining methods don’t help. As a result, many mined emeralds come from the ground with a number of inclusions and fractures that can not only dull the beauty of the stones, they can weaken the stones as well. In fact, emeralds can be notoriously difficult to cut and set if they are badly included.   Continue Reading →