The Gems from the Burning Crusade heroic dungeons haven't been scaled down yet and still have the same stats, not to much stronger than crafted gems that give secondary stats but still something example of this is Etched Tanzanite - Item - World of Warcraft which is 5 Str and 4 crit vs a flat 7 secondary stat gem, its not unique so you can use as many if you have a lot of sockets and are already using the leviathans and krakens eye for the strong prime stat gems.
Gems - World of Warcraft if you wanna see some of the other ones where Auchenai Crypts is just go down the list of dungeons and then apply filter see which one is for you.
Edit: Seems some of the bc gems are scaled down and some aren't 2 that I've obtained are the one mentioned above and Reckless Fire Opal(5 int and 4 haste) still have untuned properties while Nimble Chrysoprase is only 1crit and 1 dodge atm while on the wowhead its at 10 crit and 8 dodge if you are using the filter above, so I'm not sure why some are and some aren't but just a quick fyi for anyone who might be trying to farm some of these up on the daily lockout.
Another Item: Flame Cap - Item - World of Warcraft isn't scaled down either, and gives 23 fire sp to moves benefitting and fire class users, it doesn't share the 5 min cd with potions and can be used in combat and only has a 3 min cd while lasting for 1 min in combat!