We are definitely getting into the 0.0001% population range of people who would be able to confidently ascertain the particular tone of white gold on wrist or in hand and accurately grade it against a gen. Reps do not need to be microanalytical science props. And as reaps also mentioned, there is always going to be nuanced variation from watch to watch over time. Another thing to consider, as the watch ages and obtains the odd scratch or scuff, who is to say the absolute tone of the white gold rhodium plate is off by a fraction of a percent? Buy a rep and enjoy it, stop tormenting your ego