These are faceted Christmas garnets, also known as chromium laser YAG. We have both calibrated stones (purchased by size) and unique stones. Each unique stone is labelled with its carat weight and measurements in the photo and they can be purchased individually.
Cr:YAG, aka 'Christmas garnet' is an exotic lab-created garnet and a really unique gem even by our standards. It has a totally unique color, with a rich almost tsavorite green base and strong red fluorescence. This means that it shows a mixture of red and green flashes, and which color predominates depends on the lighting (color and angle) as well as the background it is set against. Lighter toned stones will look almost pure green when placed on a white background but change to a mix of red and green when put on a dark background. Note that the camera exaggerates the red at the expense of the green--they do look better in person. They look a bit like alexandrite or color change garnet but is also totally different and unique. This is easily one of my favorite gems, unlike anything else found in nature or any other synthetic.
Cr:YAG is used in lasers as a 'q switch', which means it is opaque until it absorbs a critical amount of radiation and then suddenly becomes transparent. This allows a laser to charge its crystal up to a higher energy level before suddenly releasing it all in a single powerfulburst instead of shooting out in a continuous beam. Pulsed lasers can be extremely powerful and are incredibly useful for all sorts of applications, from tattoo removal to cutting edge physics research. Basically, like all bad sci-fi and good RPGs you can upgrade your laser just by slapping a crystal on the end.
Like all YAG this material is ideal for jewelry with a high hardness of 8.5, no durability issues and good optical properties which make it sparkle brilliantly.