Not sure if a serial number lookup service may tell you if that exact sample shipped with glossy LCD.
•How to identify MacBook Pro models - Apple Support
•Mac Serial Number info - Lookup your Apple Serial Number:
https://www.powerbookmedic.com/identify-mac-serial.php
•MacBook Pro Unibody (non-retina) FAQ:
http://www.everymac.com/systems/apple/macbook_pro/macbook-pro-unibody-faq/
All Specs:
http://www.everymac.com/systems/apple/macbook_pro/index-macbookpro.html
Usually the included box and other information when new would tell if the higher cost glossy display
or a higher definition one were included as part of a CTO or higher build model, if offered that year.
According to Mactracker.ca database, the MB/Pro (15-inch mid-2012) display could be either:
Built-in Display-- 15.4-inch (diagonal) LED-backlit glossy widescreen display,
Optional-- 15.4-inch (diagonal) display with 1680 by 1050 pixels (glossy or antiglare)
Usually if the display has a highly mirrored dark surface with the display asleep or turned off, it may
be a Glossy display. A matte-finish or non-reflective display is indicative of a non-glossy display.
In use, a glossy LCD may be difficult to use in bright locations, since it would be reflecting a lot.
Good luck & happy computing! 🙂
edited 2x