I love the color of this stone! And the way it looks with sterling silver! I bought a bunch of these stones at a bead store, and they were labeled as "Blue Lace Agate." I'm pretty sure they're agate, but I'm not sure if they're lace agate, and I believe they are dyed. Either way, I still love the color, and was inspired to make this ring.
Available for sale here: https://www.etsy.com/listing/253478100/blue-lace-agate-rectangular-cabochon
