As I was looking through my loupe at what I thought (before testing on my gem tester because I thought for sure it was a sapphire and was looking for inclusions) was a color-changing purple sapphire due to the shift in colors from the deepest of purple to a deep blue to very deep dark green, the stone suddenly began to change to brown! It didn’t change all at once, it sort of spread. It was kind of creepy. This was while I was holding it in the tweezers. (The stone was oval if one needs to know the shape.) I had a couple more of the same stone and decided to try it again and got the same reaction. The gemstone tester was inconclusive as it was in between several different stones.
Then, this afternoon I had a clear gemstone with a line of dark blue at the tip (this was an oval stone). As I lifted the stone closer to the loupe I noticed very thin blue lines coming down the sides from the center. Once again, a change came over the stone. It began turning light blue as in an Aqua blue gemstone which it just so happened to turn out to be. The gemstone has not changed back to the clear stone with the tiny bit of blue that it started as but is now the true blue that an Aqua Marine should be. I have several more of these clear stones with the tips or some part of the stone being blue. And in one or two, the color is more of an aqua/turquoise. I have not attempted to do anything with any of these. I just want to be sure my shop isn’t haunted by the ghosts of gems past… before I start playing around anymore! Just kidding… I’m not scared… rea l l y…
Can anyone explain the changing color phenomena to me? I understand how the usual color change in the other gems happen but, this seems different, unexpected. I have a feeling it may have to do with the treatment but I could be and probably am… way off! I’m very curious as to what could have happened. Had it not happened before my eyes I seriously don’t know that I would have trusted this to be factual!
Thank you all so much.
And, HAPPY 2024 to ALL!
Thermochromic (color-change due to temperature change) zircon does exist. However, in this case, the color change is from brown to vibrant red, requires a candle flame or hotter, and the change reverses once the stone has cooled down enough.
Brown coloration are often the result of exposure to radiation. Especially in the case of smokey quartz. However, color change due to radiation should be gradual and the change is permanent.
Otherwise, the phenomenon as described sounds like a piezochromic reaction. However, i have not been able to find any literature regarding piezochromism in gemstones.
None of these three “answers” adequately answer the phenomenon as described.
Please take pictures of these stones and run the usual battery of tests. Also consider getting a radon detector for your shop.
Have you had your stones in any chemicals? Could it be possible that your stones have some kind of treatment that comes off with your hands or chemicals on your hands? I would have your shop tested to radiation. I’ve never heard of this happening and I’ve heard of some weird things. Are you sure you do not have some kind of ghost? 
I would love to see some pictures if possible.
Otter.
Thank you for your response and I apologize for the lateness of my own. Because you’re the second person to mention radiation, I ordered a Geiger counter from Amazon. Once it arrived I checked my entire basement since this is where I have my shop and the gemstones are kept. The results were negative for radiation. Whew! So, it’s back to square one.
While I didn’t take any photos of this particular stone as it changed, I did take several of a couple of stones that I recently purchased. At the time of purchase, I was told they were Padparadscha sapphires. I have a gem tester but do not tend to rely on them much mainly because, first off, they rarely give one the actual name of the stone and second, because they’re generally known to be inaccurate. However, I did use it and the dial flew straight to Sapphire! I did a specific gravity test and got a 4.06 on the stone weighing 3.74 cts. and a 3.95 for the one weighing 3.68 cts. I was disappointed at first when I looked at my chart for Sapphire and found a hard SG of 4.00. Then I looked up the SG specifically for the Padparadscha and Sapphire found that it is a bit different… there was HOPE! the SG for the Padparadscha is 3.95 - 4.10! I could let out the breath I hadn’t known I was holding all that time!
Ok, so now back to the photos and the weird part. Again, I had the two rubies on my bench under the LED light when I noticed that they too started to get a sort of shiny copper-like coat over them. I put them on a wooden stool grabbed my iPhone and began shooting picture after picture. In the pictures, you can see what looks like a fire, an orangish red changing to a darker maybe a darker red. There is a white color which at first glance I thought to be the glare from the LED lamp reflecting off of the stone. This was not the case. When I looked at the stone sitting next to it which, I would have thought would have had some sort of the same white glare… right? there was nothing. Standing in the same position, I took another photo, and the white spot was completely gone. In most of these photos, I am standing in the same position. There may be a couple that I send where I have moved around to shoot from a different perspective.
Please note, the colors inside the stone change from shot to shot as well as the colors reflecting onto the wooden surface of the stool. It is as though the gemstone is somehow magically putting on a beautiful fireworks show. This is only one of the reasons I love gemology.
Teri Steinborn
Urban Muse
p.s.
I am using a new notebook and am not certain if my iPhone has uploaded my pictures yet. If it hasn’t I’ll send them from my phone. I would love to know your thoughts. Again, it is important to look closely to understand that what you are seeing is truly emanating from within the gem and is constantly changing.
FYI, Geiger counters are unable to detect low levels of radon. You want a dedicated household radon detector for that. Avoid amazon for this one. Go here: Radon Testing Equipment & Gas Detector Systems: Pressure Gauges.
The general rule of thumb for examining gemstones is to use ambient light from a north facing window (or a south facing window in the southern hemisphere). Ideally in a color neutral room. This is especially important for color grading.
If you have a spectroscope, you may want to use it for testing your stones.
Also, LED lighting can be weird. No two brands have the same color balance, and even the same brand will have different balances. You may want to look at investing in a good UV-VIS-NIR photo-spectrometer so you can characterize your lighting. https://thunderoptics.fr/product/sma-e-spectrometer/ and the collimator: https://thunderoptics.fr/product/collimator/ . Of note, This particular photo-spectrometer has gemological applications.