Since then I've seen a lot of sellers pop up on Etsy, and a few with "diamond" rings. These rings are pretty cute, but keep in mind they are totally 2D so they look like thin bars from the top.
3 Carat Diamond Ring by jujulee, $9.95
Laminated Bling Acrylic Ring by Weaselfactory, $12.50
Diamond Ring by cbtscloset, $8
Target has jumped on acrylic jewelry, selling sets of two rings $20. They're cute, but I prefer the ones from the Etsy sellers above with the cutouts because they look more like diamonds and less like little nubs.
Acrylic Diamond Silhouette, $19.99
While we're on the topic of acrylic rings, another one of my Etsy favorites is the mustache ring.
Mustache Ring by Isette, $9.00