These are faceted erbium-doped lithium niobate with a pink base color and strong green fluorescence.
This is a really cool crystal. Lithium niobate its known for its incredible brilliance and fire, and when paired with a pink base color it makes a stunning gem. These weren't grown for that reason though--Er:LN is an emerging laser crystal, with thin wafers used for on-chip lasers. One of our partners told us they were going to start growing this material a little over a year ago, and a few months later they had their first defective crystal for us to buy. In addition to the pink color it also has surprisingly strong green fluorescence under UV.
Note that lithium niobate has a relatively low hardness of 5.5 so it should not be used in rings or other high-wear jewelry.
