Edit: Suggestion for a mana sighstone is better.
Dear Rito, I main support and jungle and buy a lot of sightstones. When I'm playing a champ that scales well off AP, however, I feel like I'm watering down my build with a HP item. Could we get an AP flavor of sightstone that builds off Amplifying Tome? Please help me reach my end game fantasy!
Zone of Endless1 votesAP sightstone wouldn't work and here's why:
Riot doesn't want Sightstone to be mandatory on every person because they want vision to be something a person sacrifices for. If you tack on AP(depending on how much) it will make the item broken. Which leave you the option of adding very little AP if you don't want it mandatory on everyone. Since AP support have very shjtty AP scaling, those little AP isn't worth buying for.
DasBruce111 votesFollowing the same formula as the HP sightstone, 20AP + ward charges for 800g isn't going to be a buy for lane champions, and while it might not be tremendously exciting for AP supports it only needs to be more attractive than 150HP.
Shardbearer1 votesA 20 AP item is a sacrifice just as much as a 150 health item is. Thinking otherwise is naive. One is slightly better than the other depending on who you are playing, but they are both still handicaps compared to any core items. Hence it being a core item regardless.
Also a bit silly to think a sightstone on someone on the team isn't mandatory. I am sure games have been won without sightstones, but I haven't been in one of them.
Occasionally what Riot say is a little unrealistic.
3tyson1 votesdear riot what do an old man and a litle girl need hp for :x 
DasBruce111 votesThe best defense is lighting your enemies on fire, after all.
3tyson1 votesand bombing them
DasBruce111 votes'merica! :o
IcyPepper1 votesEr...
I'd rather have a mana version of sightstone, since we're talking about AP support equality, not APC mage bot lane equality. :P
But in all seriousness, mana would be more beneficial early game for that 800 gold. Supports don't have a lot of gold, early game survival is better than damage for them. Mana would be much better than AP, especially for supports like Soraka (who the current hp sightstone actually hurts). Because, let's be real, how much AP would a sightstone give? 20 AP? 30 maybe? I'd rather have like 150 more mana.
DasBruce111 votesActually, I agree with this. It would be more symmetrical as well.
LaytonApprentice1 votesEvery Ryze building sightstone >.>
IcyPepper1 votesEh, 150 mana isn't going to do a lot for him, and he's have to sink 1600 total gold to get 400 mana (if this was a thing).
He'd have more options for better damage than that.
But hey, buying sightstone as a laner isn't necessarily unhealthy. Certain tanks and even bruisers can buy sightstone, even when jungling.
And it might convince people, especially mid and top laners, to buy more vision...
LaytonApprentice1 voteshttp://leagueoflegends.wikia.com/wiki/Ruby_Sightstone Upgraded to Ruby sightstone thats 400 mana + infinite wards for 1600 gold. When hes done with his laning phase or whatever he could just buy a better item in lategame.
IcyPepper1 votesshrugs
Still cuts into his early game damage a bit.
But I don't see a problem with it. Vision... is available to everyone. Granted, Ryze gets more out out of his buck with mana, but everyone has equal access to the advantages of vision. Seriously, I highly doubt people are going to complain about vision being OP. Maybe Ryze could be balanced for this sightstone, just like Lee Sin with his ward hopping? If it became OP, Ryze would only need a love-tap (not a super omega nerf).