Does the color of a hammer candle matter?

The color of a hammer candle does not significantly affect the pattern's validity; what matters is its structure and location at the bottom of a downtrend. A green hammer (close above open) is slightly more bullish than a red one because it has closed above the opening price, but a red hammer still remains valid if the structure and trend context are correct.

Focus on the long lower shadow at least twice the body length forming near a recognized support zone, rather than fixating on the body's color.