Complex sentence: Nonetheless, the commercial success enjoyed by Bertoia's diamond chair was immediate and in the mid- 50's the chairs, being produced by Knoll, sold so well, that the royalties he received for them allowed him to devote himself exclusively to sculpture.
Split into simpler sentences: Nonetheless, the commercial success enjoyed by Bertoia's diamond chair was immediate. In the mid- 50's the chairs being produced by Knoll sold so well, that the royalties Bertoia received for them allowed him to devote himself exclusively to sculpture.