Silk quality is defined by its grade. The momme define the density of the fabric. Oeko-tex and GOTS are certifications. Discover here the definitions applicable.
Definition of the silk grade:
Grade: it is simply the measure of the silk quality. The letters go from A to C, and numbers from 1 to 6. To be short, the letters A, B and C represent the length scale of silk. In other words, a grade C silk will be a silk with short threads, and a grade A with long threads. Then, the numbers refer to the thickness of the silk thread, 1 for a thin silk, and 6 for the thickest silk.
In other words, the 6A grade silk is a silk which cocoons have been specially selected to have the thickest and longest silk threads. The longer the threads are, the more it reduces the risk of defects during the weaving process, and the thicker the threads are, the more resistant they'll be over time.
Definition of the silk momme:
Momme: it is the unit of silk grammage. This measure was invented in Japan to measure the density of a silk fabric, because silk can't be measured like every other fabrics. To explain in more details, from a cocoon to another, the diameter and the length of silk threads can vary. And it is normal, because each cocoon structure is different. By knowing this, it frequently happens that two silk fabrics with a same number of threads are not of the same quality.
The momme has been created in order to measure the weight
