I'll have to check, but I think it was about 3-4 pieces and I used level 50 gems on all of them. The funny thing is that two of those dropped last night after the game kept dropping other set pieces I didn't need. I was getting the crap end of the rng stick for a good while.
Here, I found my profile - https://us.battle.net/d3/en/profile/Becoming-1392/hero/85627686
After the chest, gloves and pants dropped last night I dug up the belt out of the stash and decided to use that too. I can't tell if it shows augments on the profile because I'm on my phone at the moment.
Edit - checked in game and have 5 total ancients (including the belt) and had enough gems to augment 4 of them with level 50 so that added an extra 1,000 dex.