Denim on denim

I'm curious how others feel about wearing a denim blazer with jeans or a denim skirt? Don't do it? Only when the denim colors match exactly? Only when the denim color/shade is completely different? Only when there is "space" between the denim (IE a shirt sticking out of the bottom of the jacket separating the denim blazer from the jeans)? I'm curious because I bought a denim blazer from Old Navy but I wear jeans almost all the time, and want to get more use out of the blazer.

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