The context clue for the word diaphanous can be categorized as <u>comparison</u>.
Explanation:
As we know, context clues are, as the name suggests, clues or hints a writer gives to help readers understand the meaning of certain words or expressions. In the sentence, "The curtains in the house were diaphanous like a piece of clean glass," we have an adjective that is quite uncommon, diaphanous. What the author does, then, is he/she compares the diaphanous curtains to something else as a means of eliciting what being diaphanous means. In this case, the comparison happens by the use of simile, a figure of speech which compares two different things by using support words ("as" or "like"). It is very common for writers to use metaphors as comparison context clues as well.
From the comparison context clue given by the author, we can assume that diaphanous means clear, translucent.
