Hello, Cameron, yes, we can provide you with a 18x13 or 16x12 natural
turquoise cabochon (more to the green than vivid blue) turquoise
rectangular cab for a ring. We do have some new green turquoise mined
just last month, We have several types of green turquoise that can be
cut for your requirements. Here is a scan of one that is 15x13x3.4mm.
email us at info at nevadacassidys dot com or give us a call at
775-847-075 and let us know if we can be of further assistance.