Place the water, sugar and vanilla bean
into a saucepan. Squeeze the orange and lemon halves into the water
before adding them to the pan. Peel the pears and core them from the
bottom three-quarters of the way up. Leave the stems on. Place the pears
in the poaching liquid and cover with a clean towel to keep the tops of
the pears moist and to keep them from discoloring. Bring to a boil,
reduce to a simmer, and cook the pears until tender. The pears are done
when a fork goes in easily, but they should not get mushy. Cool and keep
the pears in their poaching liquid until ready to serve.
Spoon the granite crystals into large
wineglasses or bowls, filling them about 3/4 full. Remove the pears from
the poaching liquid and place one in each glass, setting it onto the
granite. Arrange the blueberries around the pear and garnish with a
sprig of mint.