Sterling silver is much closer to being pure silver than 14k or 18k
is to being pure gold. With so little ‘other’ metal in the alloy,
it’s much softer than gold alloys. You’ll find any part of the
jewelry exposed to wear is going to get its matte finish burnished
Your best solution may be to just design the finish so that it
avoids this problem. Keep the matte finish in places that will
experience no contact…top of rings, the bezel, in inner surface (to
give nice contrast to the high polish on the outer surface);
pendants, earrings and necklaces.
Or, design rings that have raised surfaces (wires? beads?) that will
prevent contact with other rings, furniture, etc, and give the
recessed surfaces the matte finish.
A rougher finish such as a florentine will endure much better, but
since you want a matte surface that’s not really a solution.