Sentence:  In nature we as often find the light cool as warm; also in the pictures of many of the Flemish and Dutch schools, where, as Sir Joshua himself mentions, " the silver gray or <WSD>pearly</WSD> is predominant, and are valued by the connoisseurs in proportion as they possess this excellence of a silver tint." 
Meaning of the word marked with <WSD> tags:  A pale greyish white colour, tinted with blue.