Just How Hard Is That Stone?

Upcoming Events

September 12th Ballston Arts & Crafts Market: Saturday from 10 AM to 4 PM in Wellburn Square; click here for directions. I'll see you there!

October Date TBD: It's our second anniversary! Celebrate with me at my Fall Trunk Show. Enjoy a 20% discount on all inventory. View a map.

The Mohs Scale of Hardness, or Just How Hard Is That Stone?

A few weeks ago, my friend "T" and I went to the gem show to shop for a sapphire ring to commemorate her 10th wedding anniversary.

We did some comparison shopping at various booths before she decided on a cushion-cut square tanzanite surrounded by tiny diamonds. Generally,

tanzanites are purple, and can easily be distinguished from other gemstones. This tanzanite, however, had as much blue as it could possibly have while still being considered purple. It looked beautiful on her hand, and with such a striking color, it was an easy decision for T.

Most tanzanites are purple, as shown in the photo to the left.

A few days later, when she went to have it appraised, the gemologist, whose eyes widened when he saw that amazing stone, cautioned her not to wear it every day and to be quite careful with it. He told her that tanzanite was too soft for daily wear and her ring should only be worn for special occasions.

T and I discussed his warning, which led me to the Mohs Scale of Hardness, a measurement of the scratch resistance of various minerals, or in other words, how well a stone or mineral resists scratching. It was created in 1822 by German scientist Freidrich Mohs. His list begins with the softest mineral -- talc (1), and ends with the hardest -- diamond (10). Here's a link to the scale, with some annotations.

The Mohs scale is relative, which means that each mineral isn't twice as hard as the next. For example, diamond is almost 4 times as hard as corundum (ruby and sapphire),

and 2 times as hard as topaz, yet these 3 stones are each 1 number apart on the scale. Nor is the difference between talc and gypsum the same as the differen

ce between corundum and topaz. (But for purposes of enjoying gemstone jewelry, we don't need to go any further into the science.)

Rings and bracelets take more abuse than necklaces or earrings, and so we have to be more careful with rings, especially ones that we wear every day.

Tanzanite, it turns out, is 6.5 to 7 on the Mohs scale. That makes it the same hardness as stainless steel, which suggests that tanzanite can be easily scratched. And any time a stone is surrounded by a row of smaller stones, even diamonds, those small stones can come loose if the ring is knocked into a hard surface at just the right angle.

Opals are especially sensitive, not just t

o hard knocks, but also to sun, light, and temperature. But tanzanites are more sturdy, and shouldn't be compared, as T's gemologist suggested.

So while T was correctly informed by the gemologist that her stone should be protected, he worried her a bit too much about wearing it, which is after all, why she bought it.

T and I agreed that choosing when to wear it made the most sense. Certainly not when she's playing on the floor with her kids, or when working in the kitchen. But at other times around the house, and when she goes out, she should absolutely wear -- and enjoy -- her beautiful new ring.

Click here for tips on cleaning gemstones.

--Hazel

	Of All The Beads Newsletter	September 2009 Hazel Brutsché
What's New	Upcoming Events September 12th Ballston Arts & Crafts Market: Saturday from 10 AM to 4 PM in Wellburn Square; click here for directions. I'll see you there! October Date TBD: It's our second anniversary! Celebrate with me at my Fall Trunk Show. Enjoy a 20% discount on all inventory. View a map. The Mohs Scale of Hardness, or Just How Hard Is That Stone? A few weeks ago, my friend "T" and I went to the gem show to shop for a sapphire ring to commemorate her 10th wedding anniversary. We did some comparison shopping at various booths before she decided on a cushion-cut square tanzanite surrounded by tiny diamonds. Generally, tanzanites are purple, and can easily be distinguished from other gemstones. This tanzanite, however, had as much blue as it could possibly have while still being considered purple. It looked beautiful on her hand, and with such a striking color, it was an easy decision for T. Most tanzanites are purple, as shown in the photo to the left. A few days later, when she went to have it appraised, the gemologist, whose eyes widened when he saw that amazing stone, cautioned her not to wear it every day and to be quite careful with it. He told her that tanzanite was too soft for daily wear and her ring should only be worn for special occasions. T and I discussed his warning, which led me to the Mohs Scale of Hardness, a measurement of the scratch resistance of various minerals, or in other words, how well a stone or mineral resists scratching. It was created in 1822 by German scientist Freidrich Mohs. His list begins with the softest mineral -- talc (1), and ends with the hardest -- diamond (10). Here's a link to the scale, with some annotations. The Mohs scale is relative, which means that each mineral isn't twice as hard as the next. For example, diamond is almost 4 times as hard as corundum (ruby and sapphire), and 2 times as hard as topaz, yet these 3 stones are each 1 number apart on the scale. Nor is the difference between talc and gypsum the same as the difference between corundum and topaz. (But for purposes of enjoying gemstone jewelry, we don't need to go any further into the science.) Rings and bracelets take more abuse than necklaces or earrings, and so we have to be more careful with rings, especially ones that we wear every day. Tanzanite, it turns out, is 6.5 to 7 on the Mohs scale. That makes it the same hardness as stainless steel, which suggests that tanzanite can be easily scratched. And any time a stone is surrounded by a row of smaller stones, even diamonds, those small stones can come loose if the ring is knocked into a hard surface at just the right angle. Opals are especially sensitive, not just to hard knocks, but also to sun, light, and temperature. But tanzanites are more sturdy, and shouldn't be compared, as T's gemologist suggested. So while T was correctly informed by the gemologist that her stone should be protected, he worried her a bit too much about wearing it, which is after all, why she bought it. T and I agreed that choosing when to wear it made the most sense. Certainly not when she's playing on the floor with her kids, or when working in the kitchen. But at other times around the house, and when she goes out, she should absolutely wear -- and enjoy -- her beautiful new ring. Click here for tips on cleaning gemstones. --Hazel
Can purple be a state of mind? If so, I'm in one. Take a look at this month's creations, that with 2 exceptions, are all about the color purple. Fluorite is an amazing stone. It comes in colors from nearly clear, green, blue, yellow, lavender, and purple. And the stone got its name from its ability to fluoresce when exposed to ultra-violet light. In this design, fluorite plays off the colors in the tree agate focal pendant. Click for a close-up: In this one, palest amethyst beads play off the same greens and purples in the tree agate pendant, set jauntily to one side. Click for a close-up: Deep, luscious amethyst provides contrast to the lemon jasper pears in this striking necklace. Click for a close-up: And lastly, the delicate in-between shades for which fluorite is known. Click for a close-up: The colors of these glass cubes entranced me. Click for a close-up: And a last glance at summer, with all the colors of the tropics. Click for a close-up:

Of All The Beads » Hazel Brutsché