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 Post subject: Difference between Spectrolite+RainbowMoonstone?
PostPosted: Sat Jan 09, 2010 12:09 pm 
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So Spectrolite and Rainbow Moonstone are both mulit-color Labradorite but what's the difference between them? Is it just that Spectrolite has more vibrant mulit colors and Rainbow Moonstone has more subtle colors?

Or is it that Rainbow Moonstone is a Labradorite with adularescence (color that moves along with the stone's movement) whereas the flash of color on regular Labradorlite does not move?

Or am I missing something?

THanks,
lucy


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 Post subject:
PostPosted: Sun Jan 10, 2010 7:36 pm 
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:) hello, luckyme, i thought i would take the leap because the answers to the questions are confusing..., so, here it goes.. :wink:

i believe the "rainbow" moonstone (not a "variety" of moonstone, but, a "variety" of labradorite) and spectrolite are labradorite. i think the rainbow moonstone has a multi-color or blue "sheen" that is similar to the adularescence seen in spectrolite.

please see paragraph 5 in the link below for the explanation of the phenomena seen in rainbow moonstone and spectrolite from a study on the rainbow moonstone by dr. hänni:


[url=http://www.jckonline.com/article/294337-Labradorite_s_Blue_Rainbow_Moonstone_.php]hope this helps
:wink: [/url]


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 Post subject:
PostPosted: Sun Jan 10, 2010 8:11 pm 
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I'm thinking what we really need are pictures illustrating what is being discussed here.
Labradorite and spectrolite both refer to a variety of plagioclase, usually (but not always) displaying broad flashes of iridescent color. Spectrolite originally referred to iridescent labradorite from Finland.
Image
Moonstone is (technically) a variety of orthoclase.
Image
Although both labradorite and orthoclase are feldspars, they have very distinct physical and optical properties which can be easily separated with standard gemological instruments.

Optic Character:
Labradorite: Biaxial POSITIVE
Orthoclase: Biaxial NEGATIVE

Refractive Index:
Labradorite: 1.559-1.568 (± .005)
Orthoclase: 1.518-1.526 (± .010)

Specific Gravity:
Labradorite: 2.70 (± .05)
Orthoclase: 2.58 (± .03)

There is a feldspar variety which has become available termed "rainbow moonstone". It is either transparent or translucent, displaying a billowy adularescence that is either blue or multi-colored.
Image
Often, gems referred to as rainbow moonstones will test as labradorite, not moonstone. They are a transparent or whitish variety of labradorite found in India.
Hope this helps.


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 Post subject:
PostPosted: Sun Jan 10, 2010 9:22 pm 
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:)from ms. barbra's website, on feldspar, with a nice pic of the feldspar family:
http://gemologyonline.com/feldspar.html

here's some examples from dr. smigel's website:

Image
White Indian Labradorite, also known as, "Rainbow Moonstone"
"...large quantities of a translucent white Labradorite which originates in India is widely sold under the misnomer "rainbow moonstone" at very modest prices. (True moonstone is a different, rarer and considerably more expensive, species of feldspar that has its own distinctive optical phenomenon.) As you can see, the material in question is no less attractive for bearing its improper name."
Dr. Smigel's website: (also on left-hand side of forum)
http://www.bwsmigel.info/GEOL.115.ESSAY ... orite.html


Image
Spectrolite


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 Post subject:
PostPosted: Sun Jan 10, 2010 10:54 pm 
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Barbra Voltaire wrote:
.........
Image
Often, gems referred to as rainbow moonstones will test as labradorite, not moonstone. They are a transparent or whitish variety of labradorite found in India.
Hope this helps.


Ms Barb, this stone is just drool-tiful! I have a love affair going on with moonstones behind tourmaline and garnet's backs....shhh....don't tell 'em.

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 Post subject:
PostPosted: Sun Jan 10, 2010 11:04 pm 
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Lyresa wrote:
I have a love affair going on with translucent white or colorless Indain labradorite, right behind tourmaline and garnet's backs....shhh....don't tell 'em.


Oh, Mums the word. :wink:


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 Post subject:
PostPosted: Mon Jan 11, 2010 12:41 am 
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Hmmm, that moonstone image Barbra posted looks familiar...:wink:

Ginger, while there's a lot of inexpensive Rainbow Moonstone on the market, there are very clean high-end gems that are quite costly. One source I know carries fine stones each displaying only one color: red, green, yellow, blue, etc. The image shows one of the faceted blues:

Image

Visually the thing that distinguishes "Rainbow" labradorites from orthoclase moonstone is that the color lies in a single plane and doesn't suffuse the entire stone, just like Spectrolite or generic labradorite. Tilting the stone much from the oriented color plane will cause the color to dim or disappear but they really "pop" in good lighting.

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 Post subject:
PostPosted: Mon Jan 11, 2010 1:17 am 
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Actually, as you point out ROM, colorless, transparent adularescent labradorite commands much higher prices than standard moonstones.


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 Post subject:
PostPosted: Mon Jan 11, 2010 1:54 am 
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8) thanks, ms. barbra and rom for your explanations. rom, that's a beautiful faceted rainbow moonstone-wow at the blue in the gem-looks as if its glowing!!

i have a moonstone cab ring my mother gave me that has a blue sheen and i can see other colors as well-kinda orangish, that when i tilt the stone, the blue will fade, now i'm curious if it may be a rainbow moonstone/semi-transparent adularescent labradorite? :wink: unfortunately, don't have any standard gem tools to id the stone. :cry:


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 Post subject:
PostPosted: Thu Jan 14, 2010 3:47 pm 
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Ha ha take a dip in the feldspars for fun..oh..well that only has 60% potassium so it's this type of feldspar but this one only has 30% calcium so it's that type of feldspar..sounds like they need to hook up with garnets or something :lol:

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 Post subject: Thank you!
PostPosted: Sat Jan 23, 2010 4:33 pm 
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Wow, thank you everyone for posting such in depth replies. The pics were very helpful too.

I just took my GIA Color Stones exam yesterday and I did well. So thanks again!


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 Post subject:
PostPosted: Sat Jan 23, 2010 6:58 pm 
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:smt002 congrats, luckyme!!


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 Post subject: Re: Difference between Spectrolite+RainbowMoonstone?
PostPosted: Wed May 11, 2011 9:38 am 
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good explanation. now i clearly see the difference by myself


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