A grey blazer, jacket, sports coat (whatever name you want to give it) is a timeless. A grey suit with black pants will work well to create a classic refined look, .
This pairing of a grey suit jacket and black casual pants will set you apart effortlessly. This outfit is a tested option if you're hunting for a great, summer-
You can though it's better not to. Grey suit jacket would look great with navy or black pants. Where as khaki pants would look impeccable with a navy sports .
There are a lot of ways to style the blazer. I wrote some advice on how to combine stylishly this blazer with other items. You can read here: How to Wear a Gray .
men's black jacket with grey trousers separates combinations. You can pair a jacket and trousers in similar tones without looking like you've got your suits .