'Bella' (RHS Encyclopedia of Conifers, Spicer & Auders ©2012 states this is the correct spelling.)
Abies concolor 'Bella' is a slow-growing, broadly pyramidal selection of white fir with symmetrical branching, and very good blue foliage. After 10 years of growth, a mature specimen will measure 6 to 8 feet (2 - 2.5 m) tall and 2-thirds as wide, an annual growth rate of 8 to 10 inches (20 - 25 cm)
This cultivar originated as a seedling selected in the mid-1970s by Elemér Barabits of Sopron, Hungary and introduced to the nursery trade in 1991 by Zwijnenburg Nursery, Utrecht, The Netherlands. A great deal of confusion surrounds this cultivar name. Other common spellings include 'Biella' and 'Bjella'.