What is a YAG?
YAG stands for yttrium aluminum garnet. It’s a lab-grown crystal originally intended for use in the laser industry (and still in use there today), first grown in the early 1960’s. It’s chemical formula is (mostly) Y(3)Al(5)O(12), and comes in a variety of colors due to the inclusion of a small number of atoms of another element (known as “doping”). The YAG I use in my jewelry is doped with Cerium (Ce:YAG or YAG:Ce), giving it its bright yellow color under normal light and brilliant yellow fluorescence under UV light.
YAGs are mostly used for industrial purposes these days, but was also used as an early replacement for diamonds in jewelry. Doping with other colors causes a variety of colors of YAG as well as clear (no doping), producing a range of possible colors. With a Mohs hardness of 8.5 (similar to sapphire), YAGs served as a popular diamond simulant until cubic zirconia came on the market (being cheaper to produce) in the mid-1990’s.
Today, you’ll find Ce:YAGs in specialized lasers, PET machines, and in all white LEDs. I love using them in jewelry for the unique color and fluorescence as well as the scientific background story!
You can find some of my YAG jewelry here.