The Greek that is translated as “the exact imprint of God’s very being” or similar in English is translated in Chol as “He is the one who reveals Him.”
Wilbur Aulie (in The Bible Translator 1957, p. 109ff. ) explains: “The word charaktér in Hebrews 1:3 was the word used for the impression on a coin or seal. Since the nearest Chol term ’picture’ is inadequate, the phrase ‘the very image of His substance’ was translated: ‘He is the one who reveals Him’.”