Monday, February 20, 2017

The Secrets of Gemstones

Some of you know that I am a GIA certified Graduate Gemologist.  I work part time as an appraiser for a local shop, Richard Gretz, in Corvallis.  I'm also over the top passionate about gemstones in general.

Working for a shop who's owner shares that passion, and travels all over the world to buy stones, was probably not the best idea.

A few weeks ago, I got a camera mount for my microscope.  Now, I can finally share the secret world of gemstones with you

 This series of pictures, starting with the one above and the next two, is of a colour changing gemstone known in the trade as Zultanite.  It's a form of the mineral diaspore.  It is found all over the world, but the very finest, gem grade (like this one) stones comes from a single deposit in Turkey.  The picture above is in natural light
 This is the same stone, under the microscope, with overhead fluorescent light
 And, lit from below, with incandescent light
 This is my 11.82ct Russian demantoid (andradite) garnet.  The photo above is lit from below, with incandescent light, to show the fabulous 'horsetail' inclusion that make this not only completely identifiable as both demantoid and of Russian origin, its one of the few stones who's value is greatly increased by having such a magnificent inclusion.  The picture below is of the same stone with the overhead fluorescent light on my scope

 This stone is a gem quality. .80ct Russian demantoid garnet.  In this, the 'horsetail' (byssolite or chrysotile asbestos fibres) is not in the classic, round fan type as my big one above, but still there, and still diagnostic of Russian origin.

 The next pictures, including the one above and the two below, are of my Brazilian alexandrite (chrysoberyl) .  Named for Czar Alexander II as it was supposedly discovered on the czarevitch's 16th birthday, it is rarer than most diamonds, and far more costly, especially in specimens with exceptional colour change over a carat in size.  Russian alexandrite is the most sought after, but excellent and large specimens are found all over the world, in Brazil, Sri Lanka, Madagascar and Tanzania.  The above picture is daylight
 Lit from below, incandescent
 Lit from above, fluorescent
And this is a large diamond, 2.96 cts.  Click on the picture to enlarge, so you can see a whole pile of natural inclusions particular to diamonds.  This specimen is mounted

1 comment:

  1. I've always been fascinated with gemstones and wood grain; both so beautiful when polished. Yes, I can see how that could be a dangerous pastime or vocation!