After knowing what a piercing candle is, you’ll find that they are very easy to spot on a candlestick chart. A piercing candle usually comes to rest after a downturn that is longer than five periods on the chart. Thus, on a one day candlestick chart, the trend would have to be more than 5 bars and exist at the bottom of a downtrend.
Original text: The Basics of a Piercing Pattern