Guest Author - Susan Dorling

‘Ask Our Gemology Expert’ is a regular feature at the Jewelry Collecting site, kindly provided by our guest contributor, Barbara W. Smigel, PhD., Graduate Gemologist, GIA. As site editor, my goal is to make the Jewelry Collecting site as comprehensive and interesting as possible for my visitors. Barbara’s expert guidance in this series is greatly appreciated and an invaluable learning tool for myself and others who collect gemstones and gemstone jewelry. In fact, the more I learn, the more fascinated I become by gemstones themselves, and their exciting role in jewelry design. Thanks, Barbara!
If you have a question for Barbara, please send an email to to me with subject line, Ask Our Gemologist.
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This question was sent to our gemology expert, Barbara, by Kim
f.

I purchased a tanzanite stone and I am now in the process of finding the
right mounting for it. I know that it is a softer stone, but I want to
wear it daily. So, my question is do you have any suggestions on a style
of mount that would help protect the stone.

Thank You
Kim F.
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Hello Kim,

You don't say whether you want to wear the Tanzanite in a ring or a
pendant, but I'll assume you mean a ring. As much as you probably
don't want to hear this, I would hope to dissuade you from putting the
stone in a daily wear ring. It's true that Tanzanite @ 6.5 is
relatively soft, but its real problem for daily wear is that it is not
tough. Toughness (unlike hardness which relates to scratchability ) is
a measure of how easily a stone chips or breaks.

If you have any part of the gem exposed in a ring, that part will be
subject to blows and knocks -- no matter how careful you are. The only
mounting for a daily wear ring that would be safe, would be to have the
Tanzanite "buried" in a sort of nest of gold so that no part of either
the crown or pavilion was exposed to direct contact with anything. A
custom jeweler might be able to do such a setting and make it
attractive, but any kind of standard prong or bezel setting would be
inadequate.

Using the stone in a pendant, brooch or earrings, if you had a pair,
would subject it to much less wear and tear, and you could use either a
bezel or prong mount safely.

A friend of mine who does repairs and replacements of damaged stones
for jewelers says he "could make his whole business" from damaged
Tanzanites -- they are so common.

Sorry to be the bearer of unwelcome tidings,

Barbara

Gemological Properties of Tanzanite

Makeup: Calcium, aluminum, hydroxysilicate: Ca2Al3(SiO4)3OH
Luster: Vitreous
Hardness: 6.5
Crystal structure: Orthorhombic
Fracture: concoidal to uneven
Cleavage: 1, perfect
Density: 3.35
RI: 1.69
Pleiochroism: Trichroic, blue, red-violet, yellow-green
Birefringence: .010
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We thank Barbara W. Smigel, PhD., Graduate Gemologist, GIA for her invaluable contribution to the Jewelry Collecting site. Barbara also contributes to my Fashion Jewelry site. Visit her website at Artistic Colored Stones where you can take a free gemology course or purchase custom faceted gemstones.