I was trying to decide between the black and the white versions - I went with the black sand, and am very glad I did!  I thought the black would help the silver of the "mercury glass" to really stand out, and it does!  Beautiful piece, and at a very reasonable price.  The dimensions are as described.  One of the bulbs has a bit less of the silvery "mercury" on it, but that's fine - variation is part of the "mercury glass" look.  I have not timed the sand, so I'm not sure how close to an hour it takes.  I would recommend this item to anyone wanting something interesting and unique.