California Code, Business and Professions Code - BPC § 21626

(a) A “secondhand dealer,” as used in this article, means and includes any person, copartnership, firm, or corporation whose business includes buying, selling, trading, taking in pawn, accepting for sale on consignment, accepting for auctioning, or auctioning secondhand tangible personal property.  A “secondhand dealer” does not include a “coin dealer” or participants at gun shows or events, as defined in Section 478.100 of Title 27 of the Code of Federal Regulations, or its successor, who are not required to be licensed pursuant to Sections 26700 to 26915, inclusive, of the Penal Code, who are acting in compliance with the requirements of Sections 26500 to 26585, inclusive, and 27545 of the Penal Code, and who are not a “Gun Show Trader,” as described in Sections 16620 and 26525 of the Penal Code.

(b) As used in this section, a “coin dealer” means any person, firm, partnership, or corporation whose principal business is the buying, selling, and trading of coins, monetized bullion, or commercial grade ingots of gold, or silver, or other precious metals.