Color-Change Stone: Alexandrite? Garnet? Spinel? Synthetic?

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Mix of Daylight and Energy Smart Light*

Mix of Daylight and Energy Smart Light*

Incandescent Light (Slightly more red than depicted here)*

Incandescent Light (Slightly more red than depicted here)*

Incandescent Light (More red than depicted here)*
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I bought this ring last week at Savage Mills Mall in Columbia, Maryland. The tag said the stone was Alexandrite; I really have serious doubts, but I can see why the seller might think so. However, the price I paid was NOT equal to natural Alex prices--not even close (which is why I was able to afford the ring), so I bought it on the assumption that the stone is NOT Alex, but is likely to be another kind of color-change stone (garnet, spinel, sapphire, or even a synthetic corundum: Worst-case scenario: glass. Yikes!).

Total carat weight of ring: 36.5.

14 KT, at least I think so--I can barely read the mark--but it looks like gold and passes the magnet test. The gold color in the photos is accurate. The metal has a nice "old" patina with some slight scratches on the inside. Could the ring be from the 1920's or 1940's? It kind of looks Art Deco-ish. The ring is dirty (which explains some of those spots on it), and there is some wear along the facets of the window. Obviously, the former owner(s) wore it a lot.

I'm not sure how to clean it safely.

It is solidly set--no loose prongs. Still, I worry. It looks so vulnerable.

I'm guessing the stone is 15-20 carats--it's BIG. Dimensions 14 mm round, 6.5-7 mm deep. "Ostentatious" is a great descriptor, yet it's not a girly-girl ring (part of its appeal to me).

It could be synthetic Alex, but I don't think it's Russian lab; I have a known Russian lab stone, and it's not like the stone in the ring at all. For one thing, the Russian lab is darker; the daylight color is a definite emerald, and the incandescent color is a deep purple, almost a black.

In the above photos, I was (more or less) able to capture the two main color changes. The photos aren't perfect, though; they make the stone look more like blue and purple Tanzanite.

I compared the stone under incandescent light with a known amethyst (deep purple color) stone in an antique gold setting, and my mystery stone had more red in it--more like raspberry.

Try as I might, my camera could not catch the color seen under a mix of fluorescent and daylight: a brilliant London Blue with flashes of aqua, purple, and red--it is really quite breathless. My photos show just blue.

A mix of fluorescent and daylight; unfortunately, my camera could not quite catch the stunning London Blue with aqua, purple, and red flashes*
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Other colors:

Clear day, in shadow: bluish, maybe bluish-violet.

Daylight, direct sunlight: pink with blue flashes.

Cloudy day: Medium icy blue/green, a bit like light aquamarine, although a bit darker. Depending on angle of light, sometimes a smoky spot, either in the middle or along one edge.

Setting sun (deep slant): red with purple lashes.

* Note: all photos are un-enhanced; however, they have been cropped.*