These are genuine, lab-created alexandrite gems faceted from crystals grown for lasers. Note the camera can't capture the true color! There is a red glow to these stones thanks to their strong fluorescence but it doesn't dominate like it does in the photos. These gems have flashes of red, blue and purple depending on the lighting that shift and swirl as the stone is turned.
We recently got our hands on a few alexandrite crystal heads! When alexandrite crystals are grown the top region is less pure and often has some bubbles which require it to be removed before they cut the rest of the crystal into laser rods. Fortunately it is possible to trim out pieces that are great for gem usage even if they weren't quite laser grade. These stones are really cool to look at! Their color change is strong, and shows up under different kinds of LEDs and even from looking at them with the center of your vision vs the edge. On top of that they also show rich red fluorescence which affects their color, and the angle of lighting will also cause differences in color because this material is strongly trichroic.
Alexandrite is the color-changing chromium-bearing variety of chrysoberyl, and it has been a popular gem since the first natural deposits were discovered in Russia. Its high hardness (8.5) and durability make it suitable even for ring wear, and that along with its incredible combination of colors has made it a classic. The only thing holding it back is its rarity. Oddly enough even lab-created alexandrite is quite uncommon. Synthetic alexandrite is mostly grown for industry, where it is used in some particular high-end laser systems, and the process to grow it is very expensive. Very little is produced anymore, and even when it was produced it was uncommon on the gem market. Usually instead lab-created sapphire with a color change effect was sold as alexandrite, but that material really can't hold a candle to alexandrite.
