Exceptional service (Bailley was an absolute pleasure to work with), product, and the staff is incredibly thoughtful--they even added extra o-rings.
The product itself simply oozes quality--the stone is beautifully cut and reflects light in several brilliant colors (Tanzanites are apparently known for that (:).
One thing, though--their products are pre-order, so they don't begin manufacture and subsequent shipment until the product is ordered and paid for. Mine took approx. 2 months, but they were worth the wait!