Gold surged by rupees 257 to Rs 42,428 per 10 grams in local bullion market Saturday on thin activity, as its international price closed at $1,537 an ounce, market sources said. According to Karachi Saraf Association, tola (11.664 gram) price also jumped by Rs 300 to Rs 49,500. However, silver closed unchanged at Rs 1,080 per 10 grams.