Silk

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

In-game examine text: "It's a sheet of silk."

It has a Grand Exchange buy limit of 18,000 every four hours, a high alchemy value of 18 gp, and item ID 950.

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Silk shows an active flip setup with a margin of +5 gp and 21,614 trades over the last 24 hours.

At the buy limit of 18,000 every four hours, max profit per cycle is about 90.0k gp — high margin with healthy liquidity.