Gold, Silver, Bullion and Taxes

US Gold Eagle and US Gold Buffalo coins, all weights, are not reportable for any quantity.
Foreign coins sold in quantities of 25 ounces or more are reportable. Foreign coins include, but are not limited to: South African Krugerrands, Austrian Philharmonics, Chinese Pandas, Canadian Maple Leafs, British Sovereigns, etc.
Fine bars sold in weights of one kilo (32.15 troy ounces) or more per transaction are reportable.

Silver:

Bullion coins sold in any quantity are not reportable. Examples include, but are not limited to: Mexican Libertade, US Eagles, Austrian Philharmonic, Canadian Maple Leaf, etc.
Bullion bars and rounds, .999 fine, sold in weights of 1,000 ounces or more per transaction are reportable.
Junk bags of 90% coins, $1,000 face value or greater sold in a single transaction are reportable.
As outlined here, a gold and silver bullion investor can avoid any 1099B reporting requirements by simply pursuing a buying strategy of coins that are exempt. We must add a note of caution: arranging the sale of bullion in multiple transactions to skirt the reporting requirements will expose the seller to further scrutiny and possible prosecution. A dealer that determines a seller is using a pattern of sales to avoid 1099B reporting is required to file a Suspicious Activity Report