Hello i bought this Alexandrite, but not too sure whether its real. Seller stated it is heated, but on the net i keep finding information, that heat treatment has no effect on Alexandrites. So i assume it is lab/fake stone. What is your opinion ?
Khazretgali,
Welcome to the forum!
Alexandrite has a red / green color change and is heat sensitive. I doubt heat treatment was performed, if it was truly genuine Alexandrite.
Since chromium is a key element necessary for it to be Alexandrite, a Chelsea filter would be good test. Alexandrite will always look red under the filter, no matter what light source is used. It will not verify the stone species, but it will cull out any of the imitation stones typically sold as “alexandrite”.
There are color change chrysoberyl and some lab grown corundum that can show the color change from reddish-purple to the bluish-gray, like the stone you have.
Second observation is the size of the stone. That is quite a large specimen for a genuine Alexandrite which would make it quite rare with a very large price tag.
If you haven’t seen this IGS article yet, it is a good reference.
Cheers!
Could be a color change sapphire! What is the RI? Because of size and the way it is cut most likely a synthetic sapphire.
RI is 1.744. has a IGL certificate. Contacted IGL and they confirmed its not their report.
That RI of Alexandrite if the report is right . I would take it to a Gemologist to have on RI . Then go from there!
Looks like all the fake ones coming from India.
What is its cwt? I had a big one of of those, and our jeweler friend told me that it was fake (my roommate bought it in India, and that she would have paid lots of bucks for it if it were real). An appraiser should give you an idea. If it is natural, it probably should have some occlusions. or issues. Very few natural stones will be that perfect, as I am learning, trying to sell 83 spinels, all natural, right now. I am learning a bunch of stuff, but the best of my lessons is that natural stones of any kind have been, in their creation, subjected to forces that have left scars or issues on them. A perfect stone should be suspect, unless you have something very unique here.
That stone screams that is an older Zandrite. I have the same synthetic color-change in a small test kit to check what types of light I am under.
Zandrite was originally created, trademarked, and sold by JTV.com.
The originals used traces of neodymium, lanthanum, and cerium to achieve their color change/shift effect. The ones that used neodymium will react to a magnet.
https://www.gemstones.com/gemopedia/zandrite#Zandrite-Colors
@rlynch thank you for your reply. Interesting, zandrite would fit the description the best. I also did the manget test as described, but sadly none/inert reaction. Which could point two directions… 1) a real alexandrite? highly doubt it, I paid a total of 11 $ or 2) a synthetic/lab grown alexandrite?
I guess about time to send it to a gemmologist, just for my curiosity as to what it is.
Not every Zandrite uses neodymium, so you may still have Zandrite.
Some may also have use erbium.
Also, you may need to float the gemstones to detect the magnetism. IE: set the stone on something that floats in water, then test with a magnet.
