Guide:
Southeastern Rift, south of Fullhelm Fort Wayshrine, or northeast of Trolhetta Wayshrine. Inside the Broken Helm Hollow public dungeon.
Start at Trolhetta Wayshrine. Follow the road going northeast and at the first crossroads turn left. At the second crossroads just continue forward and you will soon stand right in front of the dungeon entrance.
This and all other shards inside solo dungeons have had their locations changed due to post-launch dungeon remodeling. This one was relocated to the eastern part of the cave. This is the brightest part of the cave, since the ceiling is broken and the sunlight enhances the glow of the shard.