A fiber, ribbon or yarn comprising greater than about 90 weight percent carbon single-wall nanotubes, wherein average diameter of the single-wall carbon nanolubes is about in the range of about 0.6 nm to about 0.9 nm, wherein said fiber, ribbon or yarn is produced by (i.) forming a uniform suspension in liquid of single-wall carbon nanotubes, free of carbonaceous contaminants, made from carbon monoxide at a pressure of at least 10 atmospheres, (ii.) coagulation spinning the suspension to form the structure, (iii.) submitting the structure to tension, and (iv.) annealing the structure under a state of tension.