A new state law taking effect this week offers greater protection for those who buy precious metals in Minnesota. The law requires criminal background checks for those who deal in gold coins and other metals. Anyone convicted of a financial crime in the past 10 years will be barred from dealing. It also requires dealers to post a surety bond, which would be made available to consumers in the event of misbehavior. A recent investigation found that the unregulated industry often had dealers who were ex-convicts and con artists who misled or defrauded customers. Opponents say the law taking effect Thursday goes too far and will likely drive some smaller companies out of the state or out of business.