Gleaming Arcanocrystal
The {item:oshugun_crystalfragments} Gleaming Arcanocrystal is a toy found in The Azure Span that, when used, summons three crystals floating around you for 20 seconds with a 2-minute cooldown, obtained by looting a hidden treasure using a {item:inv_misc_notescript1c} Sorrowful Letter.
The 
Gleaming Arcanocrystal is a toy found in The Azure Span that, when used, summons three crystals floating around you for 20 seconds with a 2-minute cooldown, obtained by looting a hidden treasure using a 
Sorrowful Letter.
Guide awaiting review
Complete the Prequest
Loot a 
Dragon Isles Supply Bag from a Primal Proto-Drake to unlock the treasure map drop system. The character that looted the bag must reach Dragonscale Expedition Renown 21 for maps to begin dropping.
Obtain the Sorrowful Letter
Farm for the Sorrowful Letter, which has a low drop chance from dirt piles and expedition packs scattered across the Dragon Isles. These dig spots become visible on your minimap after reaching Dragonscale Expedition Renown 2 and 5. Be aware that some players have reported needing well over 250 attempts before the letter drops.
Buy the Small Expedition Shovel
Purchase a 
Small Expedition Shovel from Pathfinder Jeb at 47.38, 83.38 in The Azure Span. You will need this shovel to dig up the buried treasure.
Use the Sorrowful Letter
Use the Sorrowful Letter while in The Azure Span to mark the treasure location on your map.
Loot the Gleaming Arcanocrystal
Head to at 40.45, 41.36 in The Azure Span and use your Small Expedition Shovel to dig up the Forgotten Jewel Box and claim the Gleaming Arcanocrystal toy.
Tips
This treasure is part of the Treasures of The Azure Span achievement — see the video guide for a full walkthrough of all Dragonflight treasure maps.
If no maps are dropping after many attempts, verify that the character who originally looted the Dragon Isles Supply Bag has reached Dragonscale Expedition Renown 21. You can confirm this by running
/script print(C_QuestLog.IsQuestFlaggedCompleted(72708)) in-game.
