A proposed $18 million addition at the West Akron headquarters of Sterling Jewelers could result in up to 200 new jobs.The expansion would be the latest in a series at the campus of the jewelry retailer off Ghent Road, near Summit Mall, that dates to the late 1980s.Sterling — operator of Kay Jewelers, Jared the Galleria of Jewelry and other chains — has been quiet about plans for the addition, which were discussed at two Akron City Council meetings last month.David Bouffard, a vice president at Sterling’s parent company, Signet Jewelers Ltd., declined this week to offer a construction timetable or many other details.“It is a proposed expansion project that is going through an approval process, so a construction date has not been confirmed,” he said by email.