 Shares of II-VI Inc. sank 6.1 toward a six-month low in premarket trading Thursday, after the optical technology company beat fiscal third-quarter earnings expectations, but provided a downbeat profit outlook for the current quarter. Net income for the quarter to March 31 rose to 81.1 million, or 66 cents a share, from 5.9 mullion, or 6 cents a share, in the year-ago period. 