I tried wearing them on the same wrist for just one day and my regular/classic JUC (with diamonds) did scratch my Apple Watch on the display screen and the side of the aluminum housing. The scratches are quite minor and not visible from normal viewing distance, but I knew they would accumulate if I continued pairing the two. For what it’s worth, the diamonds were probably the culprit, so if you’re thinking of getting the JUC model without diamonds you might fare better. I did note that while the Apple Watch was slightly marred by the experience, the JUC looks completely unscathed! It’s a beautiful and resilient piece. I’m wearing them on separate wrists now.