Blue Nile Inc. reported yesterday 13% year-over-year sales growth in the second quarter and 32% growth in new customers. The report sent the e-retailer’s stock price up 37% in early trading today.

For the second quarter ending July 1, 2012, web-only jewelry retailer Blue Nile, No. 71 in the Internet Retailer Top 500 Guide, Blue Nile reported:

• Net sales of $91.0 million, a 13.0% increase compared with $80.5 million in the second quarter of 2011.
• Sales in the e-retailer’s largest segment, U.S. engagement rings, were $52.4 million, a 19.4% increase compared with $43.9 million last year.
• U.S. non-engagement sales increased 1.7% to $24.2 million from $23.8 million in Q2 2011.
• International sales were $14.4 million, a 12.5% jump compared with $12.8 million for the second quarter 2011.
• New customers grew 32.0% in the second quarter of 2012 compared to the second quarter of 2011. The retailer did not disclose the number of new or existing customers.
• Net income was $1.58 million, nearly a 44% drop from $2.84 million in Q2 2011.

“We are pleased to report significant revenue growth along with improved profitability, and we are especially excited about the continued acceleration in the sales of engagement products,” says CEO Harvey Kanter. “As we move forward, we are very excited about our plans to ignite growth in the sales of our non-engagement products through the evolution of our assortment.”

For the first six months of the year, Blue Nile also reported:

• Net sales of $174.1 million, up 8.3% from $160.7 million in the first half of last year.
• Net income of $1.73 million, a 67% decrease from $5.26 million in the same period of 2011.

Blue Nile projects third quarter sales of between $87.0 and $91.0 million and full-year sales of between $384.0 and $417.0 million.