Ruby

Ruby 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 13,000 every four hours, a high alchemy value of 600 gp, and item ID 1603.

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Ruby currently has a flip margin of −9 gp, which isn't profitable to flip right now despite 1,913,270 trades over the last 24 hours.

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