Emerald

The Emerald is a free-to-play Old School RuneScape item — “This looks valuable.”. Its Grand Exchange buy limit is 13,000 per 4 hours. Right now it buys at 413 gp and sells at 428 gp — a net margin of 7 gp (1.7% ROI) after the 2% Grand Exchange tax of 8 gp. High alchemy yields 300 gp.

To flip it, place a buy offer near 413 gp and a sell offer near 428 gp; the spread minus GE tax is your profit. Confidence figures are model estimates from live OSRS Wiki prices, not guarantees — flip responsibly.