Most discussion of the identification of reed quality is focused on external appearance. The fundamental problem with this approach was explained to me by Kunibert Michel when I visited him in Hanover, Germany, in 1997-98.
The Sound Quality
Sound quality and ease of playing are dependent on the diameter of the cane’s vascular bundles. The narrower the bundles, the more beautiful the tone and the greater the ease of playing. Reed durability is a function of lignin density level, with higher density associated with greater durability.
The photographs were taken at the Agricultural University of Athens by Prof. Kostas Fasseas.
Stereoscopic images 1-3 depict reeds with these characteristics which can be played immediately with a beautiful tone, while images 4-6 show reeds of lesser quality.