That's not quite true if you read the prospectus. The shares were originally issued the way you described, but every year the ETFs deduct management fees and expenses from the funds, so every year the gold and silver holdings become fractionally smaller on a per share basis.
That's not what I said, and if you are interested, I am short on gold and long on platinum -- just the opposite of what you suggest.
now we see the bid and ask gap for platinum is getting nearer. it varies between $4.00 to $6.00. and when it doesn't have transaction. the gap is $10.00 between bid and ask.