“Eleven years ago, he opened his shop.  Recently, he said, a fellow merchant on 20th street drilled into a 10-oz. bar he’d been sold to check its quality — and learned it was salted with tungsten. He warned Fadl to do the same.  Here’s what Fadl found.   Ten ounce bars are thicker, making them harder to detect if counterfeited — the standard X-rays used by dealers don’t penetrate deep enough.  Plus, the bars had been sealed and numbered. So whoever did this must be running an extremely sophisticated operation, Fadl said.”