When you trade a bearish diamond chart pattern, you should comply with the following rules:
Confirm the diamond pattern by discovering relatively significant trading volumes. Make sure the pattern is more horizontal rather than vertical. If the shape is more vertical than horizontal, you will probably look at a head and shoulders chart pattern.
Sell when the price breaks the lower right side of the diamond.
Place a stop-loss order above the last top inside the diamond shape on the chart.
Stay in the trade for a minimum bearish move equal to the size of the diamond pattern.
You can extend profits by simply adding a volume-weighted moving average. When the price breaks the VWMA upwards after completing the minimum target, you should exit the trade. If the stock is known to be more volatile, use a bigger VWMA.