Crystal key

Crystal Key is a members-only item on the OSRS Grand Exchange in the other category.

In-game examine text: "A mysterious key for a mysterious chest."

It has a Grand Exchange buy limit of 11,000 every four hours, a high alchemy value of 90 gp, and item ID 989.

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Crystal Key currently has a flip margin of −297 gp, which isn't profitable to flip right now despite 23,555 trades over the last 24 hours.

Items with negative or zero margins like this are better watched than actively flipped until the spread widens.