After a series of retail earnings from mediocre to dismal, there is one diamond in the rough: Tiffany & Co is soaring after topping estimates in its first quarter. Over the three months to April, the company earned $0.97 cents a share, $0.19 cents higher than analysts expected. Meanwhile, sales surged 13% from a year earlier to $1 billion. Management expects the good fortune to continue. For the full year ending next January, the jewelry retailer expects worldwide net sales up by a high-single-digit percentage. The company also increased its earnings guidance to between $4.15 and $4.25 a share.