Yes, the body can affect the result because these cameras use different sensor sizes. The EOS 6D is full frame, while the EOS 700D is APS-C with a 1.6x crop factor. With the same 100mm macro lens, the 700D gives a tighter field of view, which can make small subjects like jewelry appear larger in the frame. That can be helpful for close-up product shots.

So the difference is less about the lens changing and more about how each sensor records the image. Based on the community answer, for jewelry photography the 700D may be the more practical choice if you want greater apparent magnification in-camera. The 6D will show a wider view with the same lens.