I bought a few pieces of tanzanite in Cozumel and love them all. The only problem is that I insist on wearing them daily. A stone in the ring has a mark in it now and two of the eight opals in the pendant have fallen out. It's not a good idea to wear these daily but I can't help it!
Another story to ponder: I bought my first piece of tanzanite at a large retail jewler here in the states. A year later I had it appraised. They told me that it wasn't even tanzanite. It was sky blue topaz with a purple tinge to it! The jewler said they couldn't refund my money as it was over a year old and they couldn't match the ring to the receipt. The descriptions on those receipts are really vague. I got burnt!
Get familiar with tanzanite before you buy it! Go online and do your homework!