Should be plump, fresh in appearance and fairly uniform in size, clean, dry, free from leaves and stems, and with full color throughout the group.  Ripeness is indicated by the color, which may be light blue to dark black.  the berries may have a light colored bloom which is a natural protective wax, depending on the variety.  As moisture is detrimental to the quality of the berries it is important, the lack of it is essential.  Moisture may be caused by natural breakdown, decay, or mechanical injury.  Fruit should be neither green or over ripe. Fruit that is over ripe has a dull appearance, and is often soft and watery.  Berries held too long after picking have a similar appearance to that of over ripe berries and may be shriveled.    decay is indicated by the presence of mold.  Blueberries are highly perishable and must be used as soon as possible after being purchased.  To prolong the quality the berries should be purchased cold and kept cold until served.