The District of Columbia does impose sales taxes on precious metals. There are no specific exemptions for precious metals like gold or silver, so they are subject to the standard sales tax rate of 5.75% in Washington, D.C.
This means that if you purchase precious metals from a retailer located within the District of Columbia, you will be charged sales tax on the transaction. However, some online retailers located outside of D.C. may not charge sales tax to D.C. residents.