Which type of photography will you be doing more of? If macro, I'd get the 105mm. If portrait, I'd get the 85mm and supplement it with a set of extension tubes to allow very close focusing. Disclaimer: Although I used to own the 85mm, I never tried using extension tubes with it. They work better with some lenses than others.
If you choose the 85mm, look for extension tubes that support autofocus for AF-S lenses. These have all of the CPU contacts required to pass the full set of signals to AF-S lenses from the body and vice versa. You can find them on Amazon and eBay.
Ideally, though, you should get the 85mm for portrait AND a real macro lens. You don't need a macro lens that autofocuses. As long as the camera is supported (e.g., on a tabletop tripod) and the subject doesn't move, manually focusing a macro lens is easy. I highly recommend the Micro-Nikkor 55mm f/2.8 AI-S lens. This lens is still available new, but you can find used ones on eBay and elsewhere for $100-$150. With the 55mm, you'll need to get closer to the subject than with the 105mm for the same magnification, but I don't think that's a problem for jewelry. The only caveat: since this is a non-CPU lens, it won't support metering or autoexposure on lower-end bodies like the D3x00 and D5x00 series.