Featured Beyond Alexandrite Glass

Discussion in 'Pottery, Glass, and Porcelain' started by Bronwen, Nov 20, 2018.

  1. Bronwen

    Bronwen Well-Known Member

    After reading in various Antiquers threads about the usefulness of UV light in determining the nature of some materials, when I spotted little UV flashlights for sale, I grabbed one, and have had fun shining it here and there to see the effects. Most things seem just to reflect it back and glow some degree of purple. Only a few things have been surprising. One is a cowrie shell, whose dull brown patches are bright magenta under the light. Another is the 'stone' in this brooch.

    It was auctioned as green tourmaline, and is very much that color in most lighting conditions. I quickly realized when I received it this 800 silver brooch was more likely to be glass. However, unlike other examples of green glass near it in the display cabinet, this one showed an unexpected side of itself when the flashlight played its way:



    This color shift is closer to that of genuine alexandrite than I have ever seen in any other color change material, glass or stone.


    Anyone have any insight into this glass, what the additive may be? It is much richer in color than neodymium glass. Vanadium is the mystery ingredient in color change sapphires. The 800 silver suggests a European origin for the brooch.
  2. kyratango

    kyratango Bug jewellery addiction!

    Stunning! And... puzzling :joyful:
    You’ll have lot of fun with your uv torch!
  3. i need help

    i need help Moderator Moderator

  4. Any Jewelry

    Any Jewelry Well-Known Member

    Beautiful, Bronwen. I still play around with my UV light as well, I love it on rubies. most of the rubies in my keris hilt rings are Burmese, so glow-in-the-dark.;) I know, the child in me.:rolleyes:
  5. KikoBlueEyes

    KikoBlueEyes Well-Known Member

    I just bought one too based on comments from this forum - a UV flashlight not the gem - to test some purported amber than now I realize may not be. Now I will have more uses if I ever buy a ruby. I have a number of sapphires though, maybe I'll try it on them.
  6. Bronwen

    Bronwen Well-Known Member

    Not sure if it answers or raises more. It does raise the possibility that the stone is in fact stone and not glass after all. And the happier possibility that I didn't overpay for it after all. Right now my head is reeling from reading there, consulting another mineralogical reference and pulling out other stones to see how they react under the light.

    The one really grass green tourmaline I have does not turn red. As the article explains, the same color to the eye does not mean they are the same at the molecular level. The chrome diopside earrings I have turn a very dark reddish brown.

    I had already found that color change sapphires make a very dramatic shift. Under ordinary mixed lighting conditions they're a vivid purple with glints of peacock blue. Incandescent light shifts them toward hot pink. Some wavelengths of fluorescent make them look predominantly the peacock blue. The UV surprise is that when the light is shined at a stone straight on, so that it passes through and bounces back out off the back facets, the stone looks this same deep, slightly blue red as the stone under discussion, with bright green glints. If the light is held a bit to the side, so it hits the stone obliquely, it's all bright green. Tourmalines that are green due to vanadium may not fluoresce red, but sapphires colored with this metal sure as heck do.
  7. Bronwen

    Bronwen Well-Known Member

    I don't have much amber, but what I did look at, no matter how it looks under ordinary conditions, all looked milky under the UV light.
  8. Bronwen

    Bronwen Well-Known Member

    Got one unpleasant surprise. When I lost one of four small pink sapphires in a ring, I paid a fair amount to have it replaced. Whatever it is, the stone that goes dull and dark under the UV is not the same material as its three hot pink mates. :(
  9. i need help

    i need help Moderator Moderator

    Maybe @Hollyblue knows about this.
    scoutshouse, Bronwen and kyratango like this.
  10. KikoBlueEyes

    KikoBlueEyes Well-Known Member

    Hmmm. Real amber is supposed to fluoresce in the dark. I was going to sequester myself in my closet and see. I have three pieces that I know are true amber as the source was unquestionable, but two I bought at the Antique swap meet years ago from supposedly the Baltic and a cat I bought in Egypt, I was going to check. We shall see.
  11. KikoBlueEyes

    KikoBlueEyes Well-Known Member

    I know my sapphires are real as I "mined" them from the alluvial muds of Montana. You purchase bags of dirt and sort the sapphires from the soil. I did it as a hobby for several years. It was a great stress reducer after work. Of course my idea of fun is to play with rocks and water. I had some faceted. They are a pale blue so not very valuable. The best one would retail at $700.
  12. Hollyblue

    Hollyblue Well-Known Member

  13. Bdigger

    Bdigger Well-Known Member

    @Bronwen. Try looking at the stone next to candlelight or flame. If it is Alexandrite the flame will turn it red too. reduce any other ambient light as much as possible.
    judy, Any Jewelry, Bronwen and 3 others like this.
  14. Silver Wolf

    Silver Wolf Well-Known Member

    wow..can i see your burmese keris hilt?sorry oot :bookworm:
  15. scoutshouse

    scoutshouse Well-Known Member

    @Silver Wolf I'm not sure you're ready for @Any Jewelry 's keris hilt(s)(s)(s)...
    If you're prone to envy, prepare yourself!
    Last edited: Nov 20, 2018
    judy, Any Jewelry, kyratango and 3 others like this.
  16. Hollyblue

    Hollyblue Well-Known Member

    @ KikoBlueEyes

    Digging for gemstones is fun... rubies,sapphires,garnets,aquamarine,emeralds in North Carolina.Sapphires in Montana,opal in Idaho,tourmaline,kunzite,garnet in California.
    judy, Any Jewelry, kyratango and 3 others like this.
  17. scoutshouse

    scoutshouse Well-Known Member

    Where do I dig for garnets in California, @Hollyblue??
  18. KikoBlueEyes

    KikoBlueEyes Well-Known Member

    My kind of person!!!!!!!!!!!!! How about Crater of Diamonds State Park in Arkansas? and Herkimer Diamonds in New York
    judy, Any Jewelry, kyratango and 3 others like this.
  19. scoutshouse

    scoutshouse Well-Known Member

    I don't know if it was mentioned before, @Bronwen, but I was taught to use UV light to detect repairs to pottery and glass...

    And I know there are buyers out there who go over their items, ditto.
    judy, Any Jewelry, kyratango and 2 others like this.
  20. Bronwen

    Bronwen Well-Known Member

    I did notice that the glue holding together a long, slender quartz crystal that had shattered became blazingly evident. Think it is also used to detect alterations to paintings.

    We could start a reference thread for how various materials look under UV light. The one thing I have that was altered the least by far is a Native American carving of a bobcat done in a segment of walrus tusk that is old enough to be sort of butterscotch in color.
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