Right click the shape and select Format AutoShape or Format Shape, depending on which version of PowerPoint you are using. Go to the Colors and Lines tab in PowerPoint 2003, or select Fill in PowerPoint 2007. In PowerPoint 2003, click the Color dropdown, select Fill Effect, and go to the Gradient tab. In PowerPoint 2007, select Gradient Fill.

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Choose a two color gradient option for the shape, but choose the same color for each color. Change the transparency of the second color to 100%. Select From Center in the Shading Style section. Click OK to apply these changes. Next, go to the Colors and Lines or Line Color tab of the Format dialog. Change the line color to No Line.

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When you apply the color changes, the transparent area should fill the outside of the shape, and there should be no line around the shape on the PowerPoint slide. The shape should look somewhat shadowy already, but we are not done just yet.

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