Sapphires?

[riverwatch12021]

Hello all,
I'm hooked on hunting for Sapphires. I have enough itty-bitty ones to fill the bottom of my aquarium! Can't bear to throw them away with the gravel. So, I have graded my larger ones by size and the other night I was looking them over under light and there were a few that were green in daylight and red under light. A couple purple stones as well. So is this typical? They were on a white paper, spread out. This wasn't a hint of red... It jumped right off the paper at me! All rough stones. These were from a mine in Montana. I'm new at this in case you haven't guessed.

Thank y'all

 

[chrono]

Did they change under regular light or UV light?

 

[riverwatch12021]

Under UV light. So, does that mean anything?
Thanks for your reply.

 

[demantoidz]

I found this image of Montana sapphires with red fluorescence under long wave UV. I think it means there is a higher than typical chromium content, or lower than usual iron content (same as with ruby red fluorescence).

https://flic.kr/p/7uhxiK

Here is an article on this material, fig 14 shows the possible red and violet florescence.
And they confirm, for blue & purple ones at least, "When examined using long-wave UV light, blue Yogo sapphires typically show no reaction or a weak red fluorescence due to trace amounts of chromium, while violet to purple stones generally show a medium red fluorescence reaction due to higher levels of chromium (figure 14)."

Gemological Characterization of Sapphires from Yogo Gulch, Montana | Gems & Gemology

A look at the mining and distinguishing characteristics of this naturally vibrant blue sapphire.

www.gia.edu

 

[riverwatch12021]

Yes! That's exactly what they look like! Thank you for the information. I'm going to read up more on them. Very interesting.

 

[LilAlex]

My favorite blue sapphires -- the ones that look the best outdoors in diffused daylight -- have had red fluorescence. I can not tell if it's just coincidence, though.

 

[Garry H (Cut Nut)]

Color change sapphires are rare and have been becoming collectable.
They tend not to be as extreme a change as alexandrite but that is what you have
At the recent Robert Procop exhibition at the LA natural history mueseum there was a show case with some great examples.

Note the color temperature of the light changes every several seconds.

And sorry - i accidentally hit the slow mode button half way through - so Robert is growling like one of the near y dinosaurs!

 

[riverwatch12021]

How very interesting! Since learning more about these pretties, I went through some older packets I have collected over the years. I found most that didn't fluoresce at all and others that were bright purple, blue, pink and then the red! I'm going to weigh them next. I have one blue stone that is a beautiful tab and over 3.5 carats. It does have a very discernable "bubble" in the center but, it's pretty anyway. I might try to take some photos to show y'all.
Thank you for making me smarter .
Mary Ann

 

[Garry H (Cut Nut)]

How very interesting! Since learning more about these pretties, I went through some older packets I have collected over the years. I found most that didn't fluoresce at all and others that were bright purple, blue, pink and then the red! I'm going to weigh them next. I have one blue stone that is a beautiful tab and over 3.5 carats. It does have a very discernable "bubble" in the center but, it's pretty anyway. I might try to take some photos to show y'all.
Thank you for making me smarter .
Mary Ann

The fluorescence can be related to the color changes - but the color change occurs in daylight or cool light like very white LED vs warm light like warm LED or old fashioned tungsten globes and to some extent halogen light - especially older worn out halogen lights.

 

[demantoidz]

How very interesting! Since learning more about these pretties, I went through some older packets I have collected over the years. I found most that didn't fluoresce at all and others that were bright purple, blue, pink and then the red! I'm going to weigh them next. I have one blue stone that is a beautiful tab and over 3.5 carats. It does have a very discernable "bubble" in the center but, it's pretty anyway. I might try to take some photos to show y'all.
Thank you for making me smarter .
Mary Ann

OP - try viewing in a dark place under candle light. For alexandrite/Color Change garnet at least, the CC is visible under candle light. I find the warm light from some ovens can also induce the CC (quick google search says these are a type of halogen or incandescent bulbs). Yours might have a violet/pinkish/puplish CC. Photos would be great!

Here's a sapphire with such a CC.

Unheated Color Change Green-Blue to Purple "Alexandrite type" Sapphire Oval Portuguese Cut | 2.22cts | #15-1412 - Gemfix

Alexandrite type Color Change Unheated Sapphire Green to Purple Red Oval Brilliant Portuguese Cut, , GIA Report Untreated

gemfix.com