I was also amazed by the magnitude of the quantity being offered by vincent as the initial quantity for testbuy.
For one, 500 Metric Ton is already an unbelievable number, except if you are Ferdinand Marcos or his descendants or some of his minions or caretakers. Again, i dont know if these number of tons ever really existed and hoarded by a single person.
Second, testbuy is supposed to be a sample transaction where both parties are testing the waters, so to speak. For the buyers, they are still skeptical as to whether the gold item being offered for sale are genuine. Hence, the sellers would like to test the bars during the testbuy. In fact, some buyer's would have as a precondition, a pre-assay stage (stage before the testbuy). For the sellers, they would also want to test whether the buyer is a legitimate buyer and has the financial capacity to pay for the transaction. Hence, for legitimate sellers, they would always desire that the transaction be made within the bank's premises since they would like to be paid right after the final assay and they would like to be secured using the bank's facilities and assistance.
In short, both the buyer and the seller would like to test such quantities that they are most comfortable with to better serve their abovementioned objective. either they testbuy one bar or few more bars but personally i think 500metric ton is way just too much during testbuy.
Again, i dont know if such 500 metric tons are real. but we cannot discount possibilities.