Diamond

Diamond is a free-to-play item on the OSRS Grand Exchange in the other category.

In-game examine text: "This looks valuable."

It has a Grand Exchange buy limit of 11,000 every four hours, a high alchemy value of 1.2k gp, and item ID 1601.

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Diamond currently has a flip margin of −32 gp, which isn't profitable to flip right now despite 1,426,781 trades over the last 24 hours.

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