GT Advanced Technology might be adding more sapphire furnaces at Arizona plant for Apple, according to UBS Analyst Steven Chin.

Chin raised GTAT sapphire furnace installations estimations for Apple’s Arizona plant up by 30 percent from previous estimations of 1,500 furnaces to 2,000 furnaces, according to a Barron’s blog entry. He also attributed the ongoing furnace installations to Apple’s delayed fourth prepayment to GTAT.

UBS analysts also believed GTAT’s recent announcement of a 165 kilogram furnace that is to be sold to customers not involved in cover screens was “a clue on the Apple Arizona fab.” Chin believes GT has very likely installed an over 30 percent larger furnace for Apple in Arizona that can produce 200Kg+ boules.

GTAT had successfully shipped about 1 million two-inch equivalent (TIE) sapphire to one of Apple’s cover screen suppliers in April 2014, a fivefold increase from initial productions in March this year, Chin analyzed.

Although, the sapphire application for the exact Apple device remains unclear, the volume manufactured could supply 2 million iWatches per month. The same amount of sapphires manufactured could even supply 330k/ month 4.7-inch iPhone 6, and 230k/month of 5.5” iPhone 6.

The UBS analyst projected if the iPhone 6 launched in November is larger than 5.5: than TIE sapphire production will need to reach 10 million per month by September.