The reason is that once a gemologist is financially involved in the stones, it sometimes becomes hard to make an objective appraisal. "
因為人心一旦被財利蒙蔽，或涉及自己的投資，則鑑定的立場常會偏頗。如果鑑定專家受製於他人，或兼做珠寶生意，則很可能難以抗拒暴利的誘惑，故意高估或低估珠寶的價格。余玉雲執意不做珠寶買賣，堅持純顧問的立場，正是她贏得權威的最大原因。