There are few things more exciting in the world of dusty antiques than finding a “gem” of unexpected value, as attested by the continuing popularity of PBS’s “Antique Roadshow.” On Tuesday, March 14, the Beacon Hill Women’s Forum (BHWF) welcomes Lucy P. Grogan, local fine art and jewelry appraiser and auctioneer, who has appeared several times as an expert on the popular TV show. The upcoming event, dubbed “Going Once, Going Twice: The 21st Century Auction House,” will be held at 6-8 pm at Hampshire House, 84 Beacon Street. Art and Jewelry Auctioneer Lucy Grogan at BHWF