Damage means any specific defect described in this section; or an equally objectionable variation of any one of these defects, any other defect, or any combination of defects which materially detracts from the appearance, or the edible or marketing quality of the filberts. The following specific defects shall be considered as damage:
(a) Stains which are dark and materially affect the appearance of the individual shell.
(b) Adhering husk when covering more than 5 percent of the surface of the shell in the aggregate.
(c) Shriveling when the kernel is materially shrunken, wrinkled, leathery or tough.
(d) Discoloration when the appearance of the kernel is materially affected by black color.