Identifying Color Change Stone

Hello Orchidians, I have come into possession of a ring that has one
stone approximately 18x12mm in an 14K yellow gold setting. I thought
at first glance it was a very reddish amethyst, but just yesterday
noticed that it changes colors in different lighting situations. It
looks like amethyst in natural light and then placed in low or
incandescent light changes to sort of a montana blue sapphire and
raspberry rhodolite color. I’d like to view it in the sun, but
haven’t seen it for the last 2 days! (Darn Wisconsin!) I thought it
might be a tanzanite, but I’ve not seen one of this color before.
There does not seem to be any brown or green flashes to the stone. A
10 power loupe does not show any inclusions or anything that would
indicate it being glass. There is some wear to the meet points of
the facets at the table and crown facets on one end only. The rest
are clean and scratch free.

Without taking it to a GG, is there a way to eliminate what it is
not so I don’t waste money having something worthless tested? If
it’s a synthetic, I’ll reset it the way it is or sell it the way it
is. If it’s natural, I’d like to have it repolished and do something
else with it. Here is a link to a photo of it in low, incandescent
light (left photo) and in flourescent light (right photo) I’ll add a
3rd photo if the sun comes out!:

Thanks a bunch!

Mardel, I am going to break the number one rule of gemology, never
sight identify a stone. I am very certain that the stone in your
ring is a synthetic corundum Alexanderite look alike, a flame fusion
corundum that has been doped to show some color change. These
stones are available as birth stones from most large stone and
jewelry suppliers. IE Trips and Rio Grande. Given the size of your
stone, and the description of it, it is almost certainly a
synthetic. These stones were very popular some years back, and were
sold as Alexanderites, with no mention of the synthetic origin.

You should however take the stone to a good jeweler/gemologist (not
a mall store salesman) and have them take a look. The number one
rule is there for a reason. You can never be sure without at least
three definitive observations. IE Ri, SG, Visual, UV, etc. and then
sometimes you are stumped.