MADE IN U.S.A. may not have the cachet it once had, but in the realm of antiques, the phrase is coming to mean extraordinary value for well-fixed investors. When two tiny, exquisite 18th century Philadelphia tables were auctioned at Christie's in Manhattan last Saturday, the prices they fetched were breathtaking. The first item, a dainty piecrust tea table, sold for $1.2 million; the second, a rectangular pier table less than 3 ft. high, was whisked from the block for $4.6 million.
Outrageous? No, right in line with last June's auction of the most expensive piece of furniture ever sold: a $12.1...