Oct 28 (Reuters) - Gorilla Glass maker Corning

on Tuesday forecast fourth-quarter sales above analysts'

estimates, but revenue from its largest business unit that makes

fiber optic products fell short of expectations.

Shares of the Apple ( AAPL ) supplier fell more than 7% in

premarket trading after the results, though the stock is still

up about 88% so far this year.

The company's optical communications division, which

accounts for nearly 40% of total revenue, recorded net sales of

$1.65 billion for the third quarter, below analysts' average

estimate of $1.73 billion, according to LSEG data.

U.S. optical fiber companies Corning, OFS-Felite and Drake

Communications have been pressured by slower network investment

in China, where authorities in September imposed a 37.9%

anti-dumping tariff on imports of Corning's optical fiber

products and other cable providers.

The tariff move added to U.S.-China trade tensions, further

complicating operations for American technology and

manufacturing companies exposed to Chinese demand.

The results come even as Corning deepens its partnership

with Apple ( AAPL ), which in September said all cover glass for iPhones

and Apple Watches will now be made in Kentucky using Corning's

proprietary glass technology.

Its core sales in the quarter rose 14% to $4.27 billion,

compared with estimates of $4.23 billion, according to data

compiled by LSEG.

Corning said it expects fourth-quarter core sales to be

around $4.35 billion, compared with the average estimate of

$4.26 billion.

The company forecast quarterly core earnings per share

between 68 cents and 72 cents, compared with estimates of 67

cents.

(Reporting by Kritika Lamba in Bengaluru; Editing by Saumyadeb

Chakrabarty)