It's always risky to buy glasses online, but as long as you measure a pair of glasses you already have and like fit-wise, I find that it helps a lot with the process.
I went with the blue color because navy/dark blue is supposed to compliment blue eyes really well. These do the trick in my opinion! The fit is perfect, they don't slip down my nose, and they're super lightweight. I'm a petite woman with a square-ish shaped face (or heart-shaped, not sure which...) and these are the PERFECT fit. The lens height is not too big or too small. I've attached a picture because I found customer pictures to be super helpful when I was deciding which ones to buy.
They're also a matte material, which I apparently really like. I wanted a pair of rectangular glasses and these are absolutely perfect. I'm considering getting them in black too because while the blue is very versatile, I do wear black all the time.