DUBAI, July 18 (Reuters) - Gulf stock markets were mixed in narrow ranges early on Tuesday though petrochemical maker Saudi Kayan rose in response to better-than-expected second-quarter earnings. The Saudi index edged down 0.1 percent in the first half-hour as Saudi Kayan 2350.SE , the most heavily traded stock, rose 2.2 percent. Its second-quarter net profit climbed to 242 million riyals ($64.5 million) from 97.3 million riyals a year ago; analysts had on average predicted 212 million riyals.

Jouf Cement jumped 9.5 percent after shareholders approved a 10 percent capital increase via an issue of bonus shares, to be paid for with the company's retained earnings.

National Co for Glass Industries surged 7.1 percent after reporting a 224 percent leap in quarterly net profit, although operating profit actually fell sharply.

Qassim Cement fell 0.4 percent after it reported a quarterly profit of 53.2 million riyals versus 113.9 million riyals year ago; analysts had on average expected 66 million riyals.

In Dubai, the index edged down 0.2 percent after rising for seven straight sessions through Monday. Property firm DAMAC , one of the stocks which led the rally, fell back 4.3 percent.

Qatar's index slipped 0.3 percent as Masraf Al Rayan , the second-largest bank by market value, dropped 1.1 percent.

It reported flat quarterly net profit, in line with analysts' forecasts, suggesting the impact of Qatar's diplomatic crisis has so far been minor. Customer deposits were 61.21 billion riyals ($16.8 billion) at the end of June, up 5.9 percent from a year earlier but down 3 percent from the previous quarter.

Share prices were unchanged for Al Khalij Commercial Bank , which reported flat first-half earnings, and Ahli Bank , which reported a 3 percent rise in net profit for the first half.

(Reporting by Andrew Torchia) ((andrew.torchia@thomsonreuters.com; +9715 6681 7277; Reuters Messaging: andrew.torchia.thomsonreuters.com@reuters.net))