Black longsword

Black Longsword is a free-to-play item on the OSRS Grand Exchange in the weapons category.

In-game examine text: "A razor sharp longsword."

It has a Grand Exchange buy limit of 125 every four hours, a high alchemy value of 576 gp, and item ID 1297.

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Black Longsword currently has a flip margin of −5 gp, which isn't profitable to flip right now despite 1,839 trades over the last 24 hours.

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