My wife, husband, and I found cheap rings with a triquetra on them from Amazon. They were about $20. Here's the link: http://www.amazon.com/gp/aw/d/B007DNNP1I/ref=mp_s_a_1_51?qid=1444345993&sr=8-51&pi=AC_SX110_SY165_QL70&keywords=triquetra+ring

Not sure if it's what you're looking for but it may help you get an idea.