Returns or sets the degree of transparency of the specified fill, shadow, or line as a value between 0.0 (opaque) and 1.0 (clear). Read/write Single.
Remarks
The value of this property affects the appearance of solid-colored fills and lines only; it has no effect on the appearance of patterned lines or patterned, gradient, picture, or textured fills.
Example
This example sets the shadow for shape three on myDocument to semitransparent red. If the shape doesn't already have a shadow, this example adds one to it.
Set myDocument = ActivePresentation.Slides(1)
With myDocument.Shapes(3).Shadow
.Visible = True
.ForeColor.RGB = RGB(255, 0, 0)
.Transparency = 0.5
End With