GemologyOnline.com https://www.gemologyonline.com/Forum/phpBB2/ |
|
Green Tourmaline... no chrome in it, but really bright https://www.gemologyonline.com/Forum/phpBB2/viewtopic.php?f=6&t=23827 |
Page 1 of 2 |
Author: | Luca [ Thu Jul 13, 2017 11:21 am ] |
Post subject: | Green Tourmaline... no chrome in it, but really bright |
Dear friends, I have bought this green tourmaline from Namibia its about 1 carat, well cut in stepped octagon. The color is intense green, with a hint of yellow. It does not turn red under Chelsea filter, thus no chrome is in this stone. I wonder whether such a bright green is due to iron. I know, in fact, that green tourmalines are often colored by iron, but this one is particularly vivid. here some pics Thank you for all the replies |
Author: | Barbra Voltaire, FGG [ Thu Jul 13, 2017 12:43 pm ] |
Post subject: | Re: Green Tourmaline... no chrome in it, but really brigh |
Tourmaline can have so many variables when it comes to the transition metal impurities which cause color. Fabulous color! http://www.elementsmagazine.org/archive ... zzotta.pdf |
Author: | Marlow [ Thu Jul 13, 2017 1:40 pm ] |
Post subject: | Re: Green Tourmaline... no chrome in it, but really brigh |
Like it very much! Great color... Found this bright 2,20 ct in St Marie aux Mines. Sold as a "Merelani" Diopside - the dichroism was to strong and I liked it very much so I took it. With a little hope that it could be a bright green kornerupine too. At the moment they offer some. So "only" tourmaline - orign unknown - maybe Mozambique ( dealer is specialized in Tanzania gems ) or another african source. Attachment: IMG_243.jpg [ 38.3 KiB | Viewed 1949 times ] Eyeclean with very nice cutting. |
Author: | Stephen Challener [ Thu Jul 13, 2017 3:12 pm ] |
Post subject: | Re: Green Tourmaline... no chrome in it, but really brigh |
The stone in the original post looks nice but also typical of tourmaline? Maybe it's just my monitor but I don't see anything that makes me think it wouldn't be iron colored, it's just a nice example. |
Author: | Luca [ Fri Jul 14, 2017 3:29 am ] |
Post subject: | Re: Green Tourmaline... no chrome in it, but really bright |
@Barbra thank you for the suggested reading It is really interesting!!! @Marlow I really like your tourmaline with this nice mint color... I think this particolar hue is rare in a tourmaline. @Stephen Maybe my tourmaline is colored by iron. However, it seems to me different from other tourmalines I have seen before. So, I supposed that this bright green might be due to a different element. I have read that some green tourmalines (with no red reaction at the Chelsea filter) are colored by vanadium. |
Author: | Seaglow [ Fri Jul 14, 2017 2:18 pm ] | |||
Post subject: | Re: Green Tourmaline... no chrome in it, but really bright | |||
Small stones and the bigger one is included but nice color. Nigerian origin. 0.75ct. and 1.19 cts.
|
Author: | Luca [ Sat Jul 15, 2017 5:11 am ] |
Post subject: | Re: Green Tourmaline... no chrome in it, but really bright |
@Seaglow Very nice stones! |
Author: | Seaglow [ Sat Jul 15, 2017 6:59 am ] |
Post subject: | Re: Green Tourmaline... no chrome in it, but really bright |
Luca, no red fluorescence, so most likely vanadium. |
Author: | ruby302 [ Tue Jul 18, 2017 4:37 am ] |
Post subject: | Re: Green Tourmaline... no chrome in it, but really bright |
Attachment: chrome tourmaline resz.JPG [ 78.84 KiB | Viewed 1796 times ] |
Author: | Barbra Voltaire, FGG [ Tue Jul 18, 2017 2:07 pm ] |
Post subject: | Re: Green Tourmaline... no chrome in it, but really bright |
Everyone who has followed my posts over time knows that simply being colored by a specific elemental chromophore does not guarantee beauty. Modifiers like copper, chromium, are often used as hype to promote gems which would be hard to sell otherwise. |
Author: | ruby302 [ Tue Jul 18, 2017 2:53 pm ] |
Post subject: | Re: Green Tourmaline... no chrome in it, but really bright |
If i may please add-maybe not beautiful, but unique for what they are, nature adds true gems to the menu & variety to see-Ive seen some unique gems in the last few months that were not seen before or were not known of, so to speak- |
Author: | Marlow [ Tue Jul 18, 2017 4:16 pm ] |
Post subject: | Re: Green Tourmaline... no chrome in it, but really bright |
Well, sometime they are not "beautiful" but really interesting.... 2,58 ct UE Tourmaline... Attachment: IMG_284.jpg [ 60.41 KiB | Viewed 1759 times ] LED - quite close to daylight color which is a bit better and cooler green. Attachment: IMG_283.jpg [ 43.74 KiB | Viewed 1759 times ] Incandescent light - both pics Attachment: IMG_285.jpg [ 36.98 KiB | Viewed 1759 times ] |
Author: | maialetto [ Tue Jul 18, 2017 4:52 pm ] |
Post subject: | Re: Green Tourmaline... no chrome in it, but really bright |
I have one of those large UE chrome tourmalines as well. It's one of my favorite stones, I admit, but from an aesthetic point of view is so dark that under "normal" illumination is almost black. Only with strong illumination I get bright green and red sparkle. Really beautiful, but if I were to choose a stone to wear, that's just too dark. I'm always tempted to recut it, but I'm sure it won't improve it much, if at all, so I have to live with it... |
Author: | Marlow [ Tue Jul 18, 2017 11:36 pm ] |
Post subject: | Re: Green Tourmaline... no chrome in it, but really bright |
Fortunately my stones is not to dark and custom cut ( Coast to Coast ). A friend of mine, Uli Zeisberg, bought nice CC garnet rough with a visible usambara effect - first time I could see it in garnet. Greyish green bodycolor in daylight but the thicker part in the middle was greyish pink. Can't wait to see the cut stone. |
Author: | Luca [ Sun Jul 23, 2017 9:55 am ] |
Post subject: | Re: Green Tourmaline... no chrome in it, but really bright |
Thank you all for the replies, I definitely agree with Barbra that one specific chromophore (Cr, Vn, Cu) doesn't necessarily confer beauty to a stone. However, it seems to me that the trade market does take this aspect in great consideration. In particular, in my old edition (2015) of the Gem Guide, green tourmaline under 1 ct is valued 25-40 dollars for the fine quality and 40-60 dollars for the extrafine quality. BTW, I have paid my tourmaline more than 60 dollars per carat (no matter since I liked the color). On the other side, in the Guide chrome tourmaline is valued much more (125-250 dollars per carat for the extrafine quality). Thus, it seems that the presence or the absence of a specific chromophore is more important than beauty to estimate the value of a gem? Why? thank you |
Page 1 of 2 | All times are UTC - 4 hours |
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group http://www.phpbb.com/ |