If you bid on some auctions or bought some Gems or whatever, you’re probably eager to know exactly what’s going to happen to your loot. Well, it’s basically being rolled back – or, as Valve put it, “We had an issue with Gems that means we need to reset and start again.”
So here’s how it works: any Gems you created will be returned to your inventory. Any Gem purchases made from the Community Market will be reimbursed. All Auction bids have been cancelled, and the Auction has been reset. Finally, trades involving Gems will be investigated on a case-by-case basis.
So yeah. If you bought a load of Gems, you won’t have them anymore, but you will have your money. If you converted a lot of cards and wallpapers into Gems, you’ll still have those Gems. If you met some guy from Uzbekistan on a forum and he traded you a million Gems for a gift copy of Dark Souls 2 you had in your Steam inventory, then… well, Valve will have a look at that trade and decide what to do.
The Steam Holiday Auction will apparently “return shortly.” As this is Valve, that could mean anything from “tonight” to “March 2018”.