Doesn't the +XP affix on Rubys head slot seem kind of lame? The other helm effects seem a lot better (especially the 18% life one). I guess you're supposed to level jewelcrafting as you level your character so maybe you'll get the radiant ruby at like level 50-55 or something. And I doubt they'll let you give a radiant ruby to a level 1 since you would outlevel the content.
But yeah, the Amethyst seems better than the others.
The Ruby's +XP% definitely is pointless for inferno mode, but I wouldn't be surprised if blizzard allowed level 1 players use it. A level 14 rune in theory is going to be very rare/expensive so I don't think we will see many people using them at an early level, but I don't think they will stop you from doing it. It will give you +31% XP and that number is easily achieved and surpassed with +XP% gear, and they don't stop you from using it.
The Amethyst is the only gem helm bonus that gives survivability so we will surely see tons of them, especially in inferno. I plan on doing a summon heavy WD build and hope to take next to no damage, so if I can get away with it I will use an Emerald in my helm for the increase in MF. Maybe the old D2 trick of switching to your MF gear just before the boss dies will still work, if that is the case I will use both the Amethyst and Emerald
For endgame there is no point in using ruby in a helmet. Of the 3 remaining, I don't think topaz (+gold) will be very common, so it's a question of either amethyst (+% life) or emerald (+% MF). For melee characters the amethyst will probably be the gem of choice, for a ranged character the MF will be very tempting.
An interesting aspect is the synergy of using amethyst in the helm along with amethysts on other items. It shouldn't be too hard to stack perhaps +200 vitality from other item slots, so the extra % from the amethyst in the helm will be pretty massive.
The trade value of gems will most likely depend on which gems are popular for all other slots. In other words which gem type people prefer for their helm won't be driving the cost of gems. Since there are 2 different char classes that gain damage bonus from topaz and emerald I think these will be the most expensive gems.
A very good Bonus, but it will take ages till we see those gems on the Auction House.
I'm hoping that Blizzard adds more Gems to the game, to make up for the loss in collecting runes hehe
Different gems, in different slots, with different bonuses... allot of different character builds could result from this.
You could play a Demon Hunter fully focused on crit, and then level up another and get him all agility for example
Agree with MadViking, engame content that 18% HP will only be viable to the barb, and monk, anything besides them they would lean towards the MF%. and Harcore players will be stacking up hp so yea thats gonna be a need.
I plan on playing a barb and this will definitely be a priority at some point. I cannot wait to start playing around with gems and seeing the different build that come out of it. 18% is a HUGE bonus and too good to pass up. Inferno is going to require some big-time HP and this is going to be a hot item.