A gravestone doji has open, close, and low all near the same level with a long upper shadow. The long wick shows bulls drove price sharply higher but bears fully pushed it back by the close.
Strong bearish rejection at highs. Bulls rallied price aggressively but bears sold heavily into strength, pushing price back to the open. A longer upper shadow means more aggressive bear suppression.
Signal is strongest at uptrend extremes or near key resistance (win rate 62%). Enter short when the next candle confirms with a bearish close. Stop-loss above the wick's high.
Most meaningful at uptrend tops; less significant at lows. Longer shadow near important resistance = higher reliability.