Classification procedures for American Pima cotton are similar to those for American Upland cotton, including the use of HVI measurements. The most significant difference is that the American Upland color grade is determined by instrument measurement, while the American Pima color grade is still determined by highly-trained cotton classers. Different grade standards are used because the color of American Pima cotton is a deeper yellow than that of Upland (see exhibit B, American Pima colorimeter diagram). Also, the ginning process for American Pima cotton (roller ginned) is not the same as for Upland (saw ginned). The roller gin process results in an appearance that is not as smooth as that obtained with the saw ginned process.
There are six official grades (grades "1" through "6") for American Pima color and six for leaf. All are represented by physical standards. There is a descriptive standard for cotton which is below grade for color or leaf. A different chart is used to convert American Pima fiber length from 100ths to 32nds of an inch. This chart is below.