I'm merely going to echo Gemcherub. IMVHO TJC have the best grade Tanzanite at the best prices. As GC has already said, TJC are sight holders at Tanzanite One and therefore are obligated to buy a certain amount of Tanzanite. They obviously will keep a large proportion of the best gems for themselves but they do sell on. I know that certain other jewellery outlets (TV/High Street) buy Tanzanite from them!
If I were looking for a top grade Tanzanite in a great design with graded diamonds and a good gold weight/platinum weight, for a sensible price, TJC would be where I would look.
The Tanzy used in Rhapsody is the best. Some of the Iliana pieces are phenomenal too.
When you're looking at a top grade Tanzy make sure you see what it looks like while being held by the presenter but then also when it's on the hand. You sometimes find that a Tanzy looks scrumptious when being held (so light can get to the gem from all angles) but when it's put on the finger, the Tanzy becomes too dark.
You may find that if you want to buy an item for over £500 (I think), the item will only be available to phone buyers. If it's under £500 you can put it in your basket BUT the basket automatically empties overnight so unless you check out, you will lose the item. One other thing to note is that if you put items in your basket and don't check out (on a regular basis) I believe they will stop your account. So only add to your basket if you really want it.
HTH