I also saw the Z treatment for a stone, sorry I can't remember which but as said it isn't listed on the Gemporia website, where they are "so transparent" regarding treatments. I have blindly bought all sorts over the years. One big regret I have is the turquoise they sell. It was 5 years ago or more and they had Russell Twyford over as the gem expert. I fell for the clap trap and bought a couple of pieces, one Cochise turquoise and one Eyptian turquoise. I sadly never checked treatments and was taken in by the quality, rarity etc of these "natural" stones. t didn't occur to me that they were treated as they kept saying natural. A couple of years later, I was sorting my cards out and trying to make some order as they were all thrown in a cardboard box. I happened to see the letter C on one and it was the Cochise. Out of curiosity, I hunted the Egyptian card out and that too was C, so I looked it up. I can't get to the treatments page on Gemporia at the moment, don't know what is up with that. Basically, it means that the turquoise is crushed and stuck back together, probably with some glue or resin. I ws really pi$$ed off, felt cheated. Technically, it is a natural stone but is is nothing like it's original form or composition. I should have checked this out when I got the items and am kucking myself that I didn't. It put me off anything treated
I have also bought natural pearls being sold with Charlie Barron but have some serious doubts about those too. They are natural (covers a multitude of sins) but, particularly on the larger sized pearls, they never disclose how much of it's size is down to the host bead whch the nacre forms around. I hadn't thought about that before but I just don't trust Gemporia. The pearls are cheap, considering what Charlie sells his own pearls to the toffs for and I am betting there is a reason why they are so cheap. If it looks to good to be true, it usually is.