opal under ultraviolet light

[KKHK]

opal under ultraviolet light

Unread postby itsandbits1 » Mon Dec 24, 2012 1:49 am
I have been putting different opal types; from OZ and Ethiopia, and even some common opal I have found locally , under a blacklight I have and there seems to be a something common to some of them; the base material glows green. My common opal is yellowy tan and shifts to a flourescent algae green glow under the light, and so does the tan base ethiopian, and some of the Aussie material.
Interesting, anyone else have any experience with this. I'd be interested to know if the smoked wello or other treated material cancelles this effect out.
Lloyd



Re: opal under ultraviolet light

Unread postby GemAddicts » Thu Dec 27, 2012 12:36 am
Some of the Wyoming opal glows green as well. Hyalite tends to go green. Some opal will even go a pink color IIRC.




Re: opal under ultraviolet light

Unread postby gingerkid » Thu Dec 27, 2012 2:35 am
Hyalite looks cool under uv.




Re: opal under ultraviolet light

Unread postby Kerensky » Sat Dec 29, 2012 5:25 am
I just checked five specimens of Wello rough, one a transparent orange without play of colour, one near-opaque white with minimal play of colour, two translucent white with good play of colour and a brown near-transparent with very good play of colour. The orange Opal is inert under both SW and LW UV. All other four white Opals show a medium chalky-yellow at LW and two a weak chalk-yellow at SW. Matrix, where present, is inert in all tests.

P.S. For 'fireworks' under UV, best I've seen is from my Hackmanite rough. Pow!




Re: opal under ultraviolet light

Unread postby gingerkid » Sat Dec 29, 2012 11:40 pm
8) Thanks for sharing your results with us, Kerensky!

Have a pair of Hackmanite cabs that are cool to take into the sunlight. They change to a purplish color and fade when brought indoors to a grayish-white. It takes them a few minutes to change.

They are from Burma, and I think the ones from Burma and Afghanistan turn purple when exposed to sunlight/shortwave uv, and the ones from Quebec and Greenland are the opposite.



Re: opal under ultraviolet light

Unread postby itsandbits1 » Sun Dec 30, 2012 12:45 am
it's interesting to hear the results so I am going to take some pics of the change in mine but I'm not a photo editor so I'll have to figure how to put them side by side. I'd like to see some pics of any opals any one else has that do change. Specially curious about what resin or other treatments might look like. I don't have any instruments but my eyes and the uv might help see some.



Re: opal under ultraviolet light

Unread postby OpalSupreme » Sun Dec 30, 2012 1:16 am

gingerkid wrote:
8) Thanks for sharing your results with us, Kerensky!

Have a pair of Hackmanite cabs that are cool to take into the sunlight. They change to a purplish color and fade when brought indoors to a grayish-white. It takes them a few minutes to change.

They are from Burma, and I think the ones from Burma and Afghanistan turn purple when exposed to sunlight/shortwave uv, and the ones from Quebec and Greenland are the opposite.



Yea thanks a lot

I've checked this Hackmanite and this is cool gem - I found 1 from Afganistan that was really rich blue/purple on white creamy crystals - but the other i saw was also white creamy with only light pink color (I mean no in UV) - and I wonder about this rich blue Hackmanite ?? (I need to make some more research before I will buy one)

Also about the UV light
I wonder how the treated Welo can look - I mean maybe UV could help with some type of treatment ..etc
But I don't have any treated opals ;P
^I think I had 1 opal which was glass/oil filled ??? but not sure I still have



Re: opal under ultraviolet light

Unread postby Kerensky » Sun Dec 30, 2012 2:00 am

gingerkid wrote:
Have a pair of Hackmanite cabs that are cool to take into the sunlight. They change to a purplish color and fade when brought indoors to a grayish-white. It takes them a few minutes to change.

They are from Burma, and I think the ones from Burma and Afghanistan turn purple when exposed to sunlight/shortwave uv, and the ones from Quebec and Greenland are the opposite.



In general. I think you are right GK (that the tenebrescent effect reverses according to locality of origin). I have never seen an explanation for this phenomenon - that is not easily explicable. There's always more to learn....

I have four specimens (one cut gem) and have only thoroughly investigated two (the other two still being in the queue of my own stuff awaiting detailed examination. The two examines are both from Aghanistan and show strong orange fluoresence, especially under LW UV when they seem almost to catch fire and glow like hot coals!

..... So I just scuttled off and got out the two other specimens to test quickly under UV. Hmmmm.... The cut stone which shows only weak tenebrescence (possibly because of its small size of only 0.46 ct). However, it is strongly fluorescent (yellow-orange) at UV LW and weakly at SW. The other rough specimen (reportedly from Mogok) is completely inert. Hmmm.... I have had trouble before with mis-described specimens from this (well-known) dealer) from whom I no longer buy. Time to put that specimen fully through the testing wringer, methinks....




Re: opal under ultraviolet light

Unread postby SwordfishMining » Sun Dec 30, 2012 2:01 am
The Virgin Valley opal usually has a green response more from white than clear or yellowish. Short wave gets brighter action than longwave, but longwave has the most response for customers. The manganese has to be right in proportion around 5% or it can kill the UV response. Woods will generally give green but at some places have a nice yellow/orange from the caliche. The clear hyalite is bright green. When I UV the potch, most is dead or dim with one in a hundred bright and around a quarter anything. If saturated, over half has a phosphorescent green glow that can last minutes for the best ones. Non precious banks were better than precious banks for UV probably due to concentration of silica gel more than isotopes.



Re: opal under ultraviolet light

Unread postby PinkDiamond » Mon Dec 31, 2012 3:09 am
I put the blacklight bulb on the table my monitor sits on when I said I'd have to try it, but come nightfall I completely forget about doing it. I also have my LW/SW handheld unit I'll pull out, but thought having the bulb right here would remind me. Maybe I'd better make myself a note and tape it to my forehead.



Re: opal under ultraviolet light

Unread postby PinkDiamond » Sat Jan 19, 2013 10:51 am
I'm so glad you revived this thread because I did do the experiment, and completely forgot about the thread. All the opals I had available were Welos, and all were inert, but I have other types tucked away that I plan to try it on some day when I have time to dig for them.

[PinkDiamond]

Posted Feb, 2015:

Here's one Brad TGT has from a new find that will blow your mind. If I hadn't upgraded my microscope, this would have been my next choice.

A new and rather remarkable material. There are plenty of minerals that are fluorescent, that is to say they respond to UV light, either long or short wave. Furthermore, plenty of faceted stones have this response as well - diamonds are often quite fluorescent. But precious few, and esssentially none beyond the rarified collector category, are actually daylight fluorescent. That is what you have here, this opal will glow with an intense yellow-green fluorescence in regular old daylight - no special light needed!

Just profiled in the Journal of Gemmology, this material is from a find of hyalite Opal in Jalisco, Mexico. The gemmy rough is found as botryoidal masses on the matrix rock. With a little dark-field illumination, it is even possible to see this growth structure in the faceted stone, see the last photo below. It is often quite thin and larger sizes have already proven difficult to cut. That is to say, the number of stones in excess of one carat will be limited. Now, this is often said of any deposit, but from what we have read and seen, seems to certainly be the case here.

We selected this example as superb example of the find - totally clean, very well cut and with a magnificent response in sunlight. Under completely incandescent lighting, the stone is a light stray yellow shade (above, right). Indirect natural light even produces a moderate fluorescence response, but direct sunlight sets the stone aglow and gives you a stone with an almost 'highlighter' yellow color. Go one step further and add a longwave UV light and it becomes almost unreal - see below. A remarkable material that will no doubt become the preeminent example of daylight fluorescence in gems.

It's 1.11ct, and he's asking $950/ct, so it's over 1K, but is that cool or what??!!! 8)

Very cool. Expensive, but cool.

That inspired me to go out last night and get some more hyalite opal by looking with a black light (Sale in R&G for 60 & shipping LW & SW)instead of looking at what I mined after it came home. Much better finding. 100% glows LOL> No snakes out yet for a bonus, it was below freezing after dark. I have not ever noticed day glo out of the material tho.
Is that "new" Australian common opal by the old Tin Tin Bar Area? Where did the "honey opals" came from? And they were called honey not gold because they were mostly opaque instead of crystal clear?
I went and looked at the rappaport "ad" for the new common opals or it should have been called an ad. Just like Virgin Valley Precious, they ignore Oregon Fire opals too just like the Tanzanian material. Wah wah wah LOL Any of us wished we could get the prices they ask when they sell the same thing we do.
I'm sorry to report the AGGM closed without plans to reopen soon. The ISG is still operating, just not enough foot traffic in the front door before the car came thru the wall. Actually have already sold the pine cone cast I had donated and the limb round dome took a hit and it's a pocket stone now as it is just going to be a pain to slice it without going through color bars sideways somehow. Before breakage and after the rock looks about the same. If I had ever labeled any of my albums, finding a certain photo would take a lot less time.

Nice opal Pink, and nice material John.