Millimeter range for pearls

I am told that industry standard dictates that an 8-9mm pearl would
range from 8.0 to 8.9mm and a 9-10mm pearl would range from 9.0mm to
9.9mm and so fourth.

Also an 8 to 11mm strand of pearls would consist of pearls that
range from 8.0 to 10.9mm. Is this the industry standard? If I sell a
strand to my customer and say that it is 8 to 11mm, shouldn’t there
be at least one pearl that measures 11mm or more? If I bought a
strand and was told it was 8-11mm and then had it appraised and the
appraisal stated that it was 8-10mm with pearls ranging from
8.0-10.9, I would feel that I had been lied to. I know that pearls
are not as standardized as diamonds, but this practice does not rest
well with me. Please tell me what is most common in the industry.

Thank you,
JD Wriston