The Ring of an Unknown BMC Member, Common

is an Artifact item.

The chance for this item to be yielded and how many from salvaging, depends on the tier type of the item salvaged. Artifact Salvaging Chance to yield an Imbued Jewel:

Trivia
Release 88 added various common artifacts from various sources:
 * Adventure scene mountain trolls can now drop Common versions of The Ring of an Unknown BMC Member at a significant rate, and the uncommon version will drop slightly more often.