I can't tell you how many curtains I bought and returned because it's so hard to get a gray curtain that doesn't end up looking either purple-ish or is just totally blah, so I didn't have high hopes that this one would be "it," but to our surprise and delight it's just right!  The gray is a clear, true gray, and the lightly variegated weave (darker gray threads woven throughout) gives the drape some subtle added interest.  The back of the panel isn't thick or spongy like some thermal/energy saving curtains--it has a white cotton (?) backing that gives the drape weight and body, and probably offers some heat/cool insulation but may not do much for a really drafty slider.