An old post worth reading and considering:
Smoke and Mirrors - part 1 (ETA grades explained)
"ETA sells their ebauchés in 4 grades, and not all of the grades are offered for every movement. They are Standard, Elaboré, Top, and Chronometre. The Valjoux 7750 does not come in the Standard Grade. Each grade has set performance parameters, and 95% of the ebauchés delivered in a lot must be within these limits.
Standard
- adjusted in 2 positions: CH and 6H (click HERE for details on positional timekeeping terminology)
- average daily rate: +/- 12 seconds
- maximum positional variation: 30 seconds
- isochronism between 0 and 24 hours: +/- 20 seconds
Elaboré
- adjusted in 3 positions: CH, 6H, 9H
- average daily rate: +/- 7 seconds
- maximum positional variation: 20 seconds
- isochronism between 0 and 24 hours: +/- 15 seconds
Top
- adjusted in 5 positions: CH, FH, 6H, 9H, 3H
- average daily rate: +/- 4 seconds
- maximum positional variation: 15 seconds
- isochronism between 0 and 24 hours: +/- 10 seconds
Chronometre
- adjusted and timed per COSC specification (see above link under Standard) which is not much different from Top Grade
There are also upgraded parts made with different alloys and materials in the higher grades. The Standard and Elaboré calibers use Etachoc shock protection, a nickel balance wheel with a Nivarox 2 alloy hairspring, a Nivaflex NO mainspring, a steel pallet lever and escape wheel, and polyruby pallet jewels. The Top and Chronometre calibers use Incabloc shock protection, a Glucydur balance wheel with an Anchron alloy hairspring, a Nivaflex NM mainspring, a Nivarox pallet lever and escape wheel, and ruby pallet jewels."