The Emerald Shards are objects that appear in the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics. They are fragments of either the Chaos Emeralds or the Master Emerald created when the gems have been forced into shattering. Bringing them back together will reform their gestalt Emerald.
After the Master Emerald was shattered by Dr. Eggman to free Chaos, the Emerald's shards were scattered across the region. Knuckles used his treasure hunting skills and his ability to sense the Emerald's energy to find the missing shards and reassemble the Emerald. The Master Emerald was eventually broken again by Knuckles himself to prevent it from being stolen by either Eggman or Rouge. Knuckles went in search for the shards but so did Rouge who later fought him over them. She later reluctantly gave the shards she collected to Knuckles after he saved her life.
The Chaos Emeralds were later crushed into shards by Eggman to power his robots. Sonic the Hedgehog and other heroes manage to destroy the robots, retrieve all the shards, and restore the Emeralds for Emerl to absorb and gain more of a personality.